Item 1A. Risk Factors

This report contains forward-looking statements and other prospective information relating to future events. These forward-looking statements and other information are subject to risks and uncertainties that could cause our actual results to differ materially from our historical results or currently anticipated results, including the following:

Risks Related to Our Dependence on Government Contracts

We expect a substantial percentage of our future operating revenues to come from contracts with the U.S. Government for the provision and maintenance of the stockpile of TPOXX® built under the 19C BARDA Contract. If the U.S. Government does not enter into such a contract, or if such contract is materially delayed or smaller than the 19C BARDA Contract, our long-term business, financial condition and operating results could be materially harmed.

The success of our business and our operating results for the foreseeable future will be substantially dependent on the U.S. Government’s commitment to maintaining or expanding its stockpile of TPOXX®. Failure to secure in a timely manner and perform additional U.S. Government contracts after the 19C BARDA Contract to substantially maintain or expand the U.S. Government stockpile of TPOXX® could have a material adverse effect on our long-term business, financial condition, results of operations, including losses due to potential inventory write-offs, and prospects. Additionally, the 19C BARDA Contract does not necessarily increase the likelihood that we will secure future comparable contracts with the U.S. Government.

Government contracts require ongoing funding decisions by governments. A substantial percentage of our potential future revenues are expected to come from government contracts. The majority of potential revenue under any future U.S. Government contract will likely be tied to options that may or may not be exercised at the sole discretion of the U.S. Government. Failure of the U.S. Government to exercise its options under a new procurement contract to supply TPOXX® to the U.S. Government could cause our business, financial condition, results of operations and prospects to be materially harmed.

Government-funded contracts often consist of standalone procurement orders or a base period of performance followed by options for the performance of certain future activities. The value of goods and services subject to options may constitute the majority of the total value of the underlying contract, as in the case of the 19C BARDA Contract as well as any new contract to continue supplying TPOXX® to the U.S. Government.

The funding of government programs, which fund BARDA’s purchases under the 19C BARDA Contract and are expected to fund any new contract to supply TPOXX® to the U.S. Government, is subject to Congressional appropriations, generally made on a fiscal year basis even though a program may continue for several years. Our government customers are subject to political considerations and budgetary constraints, which result in uncertainties as to continued funding of their ongoing programs, including SIGA’s contracts.

As of December 31, 2025, all of the options to which most of the contract value of the 19C BARDA Contract is tied have been exercised. There is no guarantee that we will be able to enter into a new contract to supply TPOXX® to the U.S. Government, or if we do, whether the U.S. Government will exercise its options under such new procurement agreement. If the U.S. Government fails to exercise its options under such new procurement agreement, if any, our business, financial condition, results of operations and prospects may suffer materially.

Government procurement contracts are mostly set at fixed prices determined at inception of the contract based on estimates of the time, resources and expenses required to perform these contracts. If our estimates are not accurate, we may not be able to earn an adequate return or may incur a loss under these arrangements.

Previously exercised options under our government procurement contracts, including the 19C BARDA Contract, were predominately fixed price. We expect that any future contracts with the U.S. Government and foreign governments for TPOXX®, as well as contracts for other biodefense product candidates, would also be predominantly fixed-price arrangements with potential moderate annual increases. Under a fixed-price contract, we are required to deliver our products at a fixed price determined at the inception of the contract regardless of the actual costs we incur, and to absorb any costs incurred in satisfaction of our obligations. Our failure to secure financial terms, including price, generally consistent with our prior agreements, anticipate significant technical problems, estimate costs accurately or control costs during performance of a fixed-price contract could reduce the profitability of such contract, or if severe, cause a loss, which could in turn negatively affect our operating results.

Laws and regulations affecting government contracts and grants might make it more costly and difficult for us to successfully conduct our business.

Our business with the U.S. Government, international governments, and any future business with state and local governmental agencies is subject to specific procurement regulations and a variety of other legal and compliance obligations. These laws and rules include those related to procurement integrity, rates and pricing of services and goods to be reimbursed by the U.S. Government, export control, government security regulations, employment practices, protection of the environment, accuracy of records and the recording and reporting of costs, and foreign corrupt practices. Among the most significant government contracting regulations that affect our business are:

Table of Contents

Compliance with these obligations increases our performance and compliance costs. Failure to comply with these regulations and requirements could lead to suspension or debarment, for cause, from government contracting or subcontracting for a period of time and could result in significant civil or criminal penalties. The termination of a government contract as a result of our failure to satisfy any of these obligations would have a material negative impact on our operations and harm our reputation and ability to procure other government contracts or grants in the future.

Unfavorable provisions in government contracts and grants, some of which may be customary, may harm our future business, financial condition and potential operating results.

Government contracts and grants customarily contain provisions that give the government substantial rights and remedies, many of which are not typically found in commercial contracts, including (but not limited to) provisions that allow the government to:

• control or prohibit the export of products.

Generally, government contracts, including the 19C BARDA Contract, contain provisions permitting unilateral termination or modification, in whole or in part, at the government’s convenience. Under general principles of government contracting law, if the government terminates a contract or grant for convenience, the terminated company may recover only its incurred or committed costs, settlement expenses and profit on work completed prior to the termination. If the government terminates a contract or grant for default, the defaulting company is entitled to recover costs incurred and associated profits on accepted items only and may be liable for excess costs incurred by the government in procuring undelivered items from another source. Our government contracts and grants could be terminated under these circumstances.

A U.S. Government shutdown could materially adversely affect our business, results of operations, and financial condition.

Each year, the U.S. Congress must pass all spending bills in the federal budget. If any such spending bill is not timely passed, a government shutdown may close many federally run operations, and halt work for federal employees unless they are considered essential or such work is separately funded by a continuing resolution or by industry.

A significant portion of our revenue is derived from contracts with U.S. federal agencies. The U.S. continues to face a changing geopolitical environment, along with certain fiscal and economic challenges, and uncertainty exists regarding how future budget and program decisions will unfold. During periods of federal government shutdowns, many government agencies and contracting offices cease operations or operate at reduced capacity. These shutdowns may delay funding decisions, new contract awards, contract modifications, and may result in the suspension of ongoing work under existing contracts.

In the event of a prolonged shutdown, we may experience delays in securing new procurement contracts, which could result in reduced revenue. Even after government operations resume, it may take additional time for normal contracting activities to resume.

Government shutdowns can also create uncertainty in federal budgeting and procurement priorities, which could reduce future opportunities for our products. The timing and duration of any shutdown are unpredictable, and we cannot estimate the ultimate effect on our business. Any prolonged or repeated shutdowns could have a material adverse effect on our financial condition, results of operations, and ability to execute our strategic objectives.

Table of Contents

Our business could be adversely affected by a negative audit by the U.S. Government.

U.S. Government agencies, such as the Defense Contract Audit Agency (the “DCAA”), routinely audit and investigate government contractors. These agencies review a contractor’s performance under its contracts and grants, cost structure, and compliance with applicable laws, regulations and standards.

The DCAA also reviews the adequacy of, and a contractor’s compliance with, its internal control systems and policies, including the contractor’s purchasing, property, estimating, compensation and management information systems. Any cost found to be improperly allocated to a specific contract will not be reimbursed, and such costs already reimbursed must be refunded. If an audit uncovers improper or illegal activities, a contractor may be subject to civil and criminal penalties and administrative sanctions, including termination of contracts, forfeiture of profits, suspension of payments, fines and suspension, debarment or prohibition from doing business with the U.S. Government. Such actions could materially damage our business and could also negatively affect our reputation.

Risks Related to Regulatory Approvals

If we are not able to obtain regulatory approvals for certain additional indications of TPOXX® from the FDA, we may not be able to realize the full benefits of any U.S. Government contracts or may not be able to commercialize such indications other than through existing sales to the U.S. Government, and our ability to generate future revenue could be materially impaired.

The development and commercialization of additional indications for TPOXX® in the U.S., such as use for smallpox post-exposure prophylaxis ("PEP"), including the testing, manufacture, safety, efficacy, recordkeeping, labeling, storage, approval, advertising, promotion, sale and distribution, are subject to comprehensive regulation by the FDA and other regulatory agencies in the United States and by comparable authorities in other countries and jurisdictions. We could fail to achieve FDA or other regulatory approval of certain indications of TPOXX®, or there could be delays in such approval of TPOXX®, or the approved labeling for such indications of TPOXX® may differ from expectations. For example, in connection with a potential FDA label expansion of oral TPOXX® for an indication covering PEP, we completed an immunogenicity trial in 2023 and originally targeted a supplemental NDA submission in 2024. Because samples from that trial are being reanalyzed by the U.S. Centers for Disease Control and Prevention which has been impacted by recent U.S. Government shutdowns, the Company is now targeting a supplemental NDA submission within the next twelve months.

Failure to obtain regulatory approval of the PEP indication may prevent us from getting procurement orders from the U.S. Government for the post-exposure prophylaxis indication and may impact other regulatory authorities' future review of other indications of TPOXX®, which in turn, could adversely impact potential sales of TPOXX® in other countries, and such delays or required alterations to regulatory applications could also have a material adverse effect on our future revenue opportunities.

Failure to obtain regulatory approval for new formulations of TPOXX® in the U.S.would prevent us from commercializing TPOXX® in other than the oral and intravenous formulations for smallpox treatment.

We have received FDA approval for the oral and intravenous formulations of TPOXX® in the U.S. for the treatment of smallpox. We have not received FDA approval for the liquid suspension/pediatric formulation or any other formulation of TPOXX®. Because pharmaceutical manufacturers are only permitted to commercialize in the U.S. formulations that have received FDA approval (or in other jurisdictions according to their applicable regulatory and legal frameworks), any regulatory or legal setbacks as described above could have an adverse impact on our ability to sell TPOXX® in other formulations.

Failure to maintain existing regulatory approvals or obtain future regulatory approvals in additional international jurisdictions could prevent us from marketing our products in certain jurisdictions abroad.

To market our products in certain foreign jurisdictions, we need to maintain existing regulatory approvals or may need to obtain additional regulatory approvals and comply with numerous and varying regulatory requirements. The approval procedures vary among countries and can involve additional testing and differing manufacturing or labeling requirements. Coming into compliance with and maintaining compliance with such requirements may take substantial time, including prior to approval, and delay commercial activities in those jurisdictions.

The foreign regulatory approval process may include all of the risks associated with obtaining FDA approval for expanded indications or new formulations of TPOXX®. We may be unable to maintain existing regulatory approvals or may not be successful in obtaining additional foreign regulatory approvals on a timely basis, if at all. Regulatory approval by the FDA, which we obtained for oral and IV TPOXX®, and by Health Canada, for oral TPOXX®, in each case for the treatment of smallpox, or by additional foreign regulatory authorities such as European Medicines Agency (EMA), the Japanese Pharmaceuticals and Medical Devices Agency, and the U.K. Medicines and Healthcare Products Regulatory Agency (MHRA), which we obtained for oral TPOXX® for the treatment of smallpox, monkeypox ("mpox"), cowpox, and vaccinia complications following vaccination against smallpox, does not ensure continued approval in those jurisdictions or approval by additional regulatory authorities in other foreign countries or jurisdictions or by the FDA for additional indications or new formulations.

The EMA and MHRA approved TPOXX® under “exceptional circumstances” under the brand name Tecovirimat-SIGA. These regulators granted marketing authorizations under “exceptional circumstances” because it was not possible to obtain complete efficacy and safety information about the product due to the rarity of smallpox and other orthopoxviruses and because ethical considerations prevented conducting the necessary clinical studies. The Tecovirimat-SIGA marketing authorizations under “exceptional circumstances” are subject to certain specific obligations to gather additional data post-approval to help confirm the product’s safety and efficacy. All “exceptional circumstances” marketing authorizations are subject to annual reassessments that consider whether data generated pursuant to the specific obligations continue to confirm its positive benefit-risk profile. These annual reassessments determine whether the product’s marketing authorization should be maintained, changed, suspended, or withdrawn based on its benefit-risk profile.

Table of Contents

On July 24, 2025, the EMA’s Committee for Medicinal Products for Human Use (CHMP) closed its third annual reassessment for Tecovirimat-SIGA and initiated a referral procedure for the product following questions over its effectiveness in the treatment of mpox. These questions were raised following receipt of results from certain non-SIGA sponsored clinical trials evaluating tecovirimat as a potential mpox treatment including the PALM007 and STOMP clinical trials. In the referral procedure, CHMP reviewed all available data on the safety and efficacy of Tecovirimat-SIGA for all its authorized indications in order to make a recommendation to the European Commission whether the marketing authorization should be maintained, modified, suspended or withdrawn. The CHMP is expected to meet in March to issue its recommendation. We expect the CHMP will confirm the positive benefit-risk balance of Tecovirimat-SIGA as a treatment for smallpox, cowpox, and vaccinia complications, and maintain those indications in the product label. Regarding mpox, based on the results of the mpox clinical trials, we expect the CHMP will recommend withdrawal of the mpox indication. In the UK, Tecovirimat-SIGA is undergoing an annual reassessment by the MHRA. This reassessment, which is ongoing, is substantially similar to the EMA’s annual reassessment process and could result in a similar outcome.

If the CHMP recommends withdrawal of the mpox indication, and European Commission adopts the recommendation of the CHMP, it could negatively impact our anticipated revenue from Tecovirimat-SIGA and could have a material adverse effect on our business, financial condition, results of operations and growth prospects.

In addition, failure to obtain or maintain approval in one jurisdiction may impact our ability to obtain approvals elsewhere. We may not be able to maintain existing approvals or may be unable to file for or receive necessary regulatory approvals to commercialize our products in new markets, in which case, our addressable market may be reduced and our ability to realize the full potential of our products and product candidates may be harmed and our business, financial condition, results of operations and prospects may be adversely affected.

Risks Related to Commercial and International Activities

Changing political or social factors and opposition, such as protests and potential related litigation, may delay or impair our ability to market TPOXX® and any other biodefense product candidates and may require us to spend time and money to address these issues.

Products developed to treat diseases caused by or to combat the threat of bioterrorism or biowarfare are subject to changing political and social environments. The political and social responses to bioterrorism and biowarfare have been unpredictable and much debated. Changes in political leadership, such as the latest change in the U.S. Presidential administration, as well as changes in the perception of the risk that military personnel or civilians could be exposed to biological agents as weapons of bioterrorism or biowarfare may delay or cause resistance to bringing investigational products to market or limit pricing or purchases of approved products, any of which could materially harm our business.

Lawsuits, protests or other negative publicity may adversely affect the degree of market acceptance of, and thereby limit the demand for, TPOXX® and any biodefense product candidates. In such event, our ability to market and sell such products may be hindered, the commercial success of TPOXX® and other products we develop may be harmed and we may need to expend time, attention and resources addressing such legal or publicity issues, thereby reducing our revenues and having a material adverse impact on our business.

Table of Contents

Our ability to grow our business partly depends on our ability to achieve recurring sales of TPOXX® to customers other than the U.S. Government, which may increase our exposure to risks associated with conducting business in international markets.

An element of our business strategy is to sell TPOXX® internationally to foreign governments on a recurring basis. These non-U.S. Government customers include foreign governments, as well as state and local governments, non-governmental organizations focused on global health like the World Health Organization, health care institutions like hospitals (domestic and foreign) and certain large business organizations interested in protecting their employees against global threats and protecting first responders in cases of emergencies.

If we fail to obtain recurring sales of TPOXX® to customers other than the U.S. Government, our business and opportunities for growth could be limited.

In addition, the expansion of our international presence may increase certain risks, which include:

• regional safety and security considerations;

• increased management and infrastructure costs.

See the risk factor below titled “The Company is subject to complex and changing laws and regulations worldwide, which exposes the Company to potential liability, increased cost, and other adverse effects on the Company’s business” for more discussion of this risk. We cannot predict the ultimate impact such events might have on the Company’s business, financial condition and results of operations.

We reacquired international promotional rights and we may be unable successfully to expand our internal international sales and marketing capabilities or enter into agreements with third parties outside of the U.S.

Pursuant to the International Promotion Agreement described under “Business,” we previously granted a third party, Meridian Medical Technologies ("Meridian") exclusive rights to market, advertise, promote, offer for sale, or sell oral TPOXX® in all geographic regions except for the United States (the “Territory”). In June 2024, we reacquired international promotional rights from Meridian. Our ability to maintain existing international customer relationships and contracts as well as generate future international relationships and contracts will depend on our ability to identify, hire and train qualified personnel. At present, we continue to adjust the staffing and key focal points of the international marketing organization; as such, the build out of the international marketing organization is subject to additional refinements and adjustments.

For contracts with international customers that were originated by Meridian in prior years and remain active, we are reliant on Meridian to collect payments from such customers, and to remit to us our share of such payments.

Under the terms of the Amended International Promotion Agreement, Meridian remains responsible for collecting payments from customers under certain legacy contracts and remitting such payments to us on a quarterly basis. As a result, we rely on Meridian’s ability to collect and remit payment to us in a timely manner. Meridian could fail to perform such obligations adequately, cease operations abruptly or become insolvent, or our relationships with Meridian may otherwise change adversely. Any of the foregoing could adversely impact our business, financial condition and operating results as a result.

Although TPOXX® is currently stockpiled by certain governments and not sold commercially, in the future we may be required to perform additional clinical trials or change the labeling of TPOXX® if we or others identify side effects after a product is on the market, which could harm future sales of such product.

If we or others identify side effects of any approved product, or if manufacturing problems occur:

• regulatory approval may be withdrawn;

• changes to or re-approvals of manufacturing facilities we use may be required;

Table of Contents

• sales of the affected products may drop significantly;

• our reputation in the marketplace may suffer; and

• lawsuits, including class action suits, may be brought against us.

Any of the above occurrences could harm or prevent future sales of the affected product or could increase the costs and expenses of commercializing and marketing these products, which could adversely affect our business, financial condition and results of operations.

We are subject to complex and changing laws and regulations worldwide, which exposes us to potential liability, increased cost, and other adverse effects on our business.

Some laws and regulations governing our business, including the FCPA and many other global anti-corruption laws, may hold us liable for the actions of our employees as well as those of our third-party partners. Although we have implemented policies and procedures designed to ensure compliance with applicable laws and regulations, there can be no assurance our employees, contractors, third parties or agents will not violate such laws and regulations or our policies and procedures.

Failure to comply with such laws and regulations could adversely affect our business, reputation, financial condition, or ability to procure government contracts. Indeed, violations of the FCPA can result in significant civil and criminal penalties that can be levied on us and its executives. Indictment alone under the FCPA can lead to suspension of the right to do business with the U.S. Government until the pending claims are resolved and conviction under the FCPA can result in long-term disqualification as a government contractor. The SEC may also suspend or bar issuers from trading securities on U.S. stock exchanges for violations of the FCPA.

We have incurred in the past, and could incur net losses in the future, including if we fail to enter into a new procurement contract with the U.S. Government.

While we believe our current cash position is strong, our ability to continue to fund future operations will be substantially impacted by potential cash flows from any new procurement contract with the U.S. Government. If we fail to enter into a new U.S. Government procurement contract or cash flows from such procurement contract are significantly delayed or significantly different from expectations, or if operating expenses or other expenses meaningfully exceed our expectations or cannot be adjusted accordingly, then our business, financial condition, results of operations and prospects could be materially adversely affected.

Table of Contents

Risks Related to Manufacturing, Storage and Our Dependence on Third Parties

We currently rely on third parties for manufacturing and raw materials of TPOXX® and for managing our inventory. If these third parties do not perform as contractually required or as we expect, and we are unable to find an alternative third party to provide these services, we may not be able to successfully satisfy our obligations under any contracts, including the 19C BARDA Contract and any future U.S. Government procurement contract, and our business would suffer.

We currently rely on third-party manufacturers and service providers to provide raw materials and manufacture, package, test and ship TPOXX®. Under the 19C BARDA Contract, we are responsible for the performance of these third-party contractors, and our contracts with these third parties give us certain supervisory and quality control rights, but we do not exercise day-to-day control over their activities.

If a third-party provider fails to comply with applicable laws and regulations, fails to meet expected deadlines, fails to conduct trials in accordance with regulatory requirements or our stated protocols, experiences shortages or delays, or otherwise does not carry out its contractual duties to us, or encounters physical damage or natural disaster or disruptions at its facilities, our ability to meet our obligations under any contract including the 19C BARDA Contract or any future U.S. Government procurement contract, or to develop, obtain approval of and commercialization of other indications of TPOXX® or other drug candidates, could be significantly impaired or delayed. We do not currently have the internal capacity to perform these important functions, must contract with alternative third parties if our existing third-party providers are unable to fulfill their contractual duties, and may not be able to maintain commercial arrangements for these services on reasonable terms.

In addition, the facilities used by our third-party manufacturers must be approved by the FDA and comparable foreign regulatory authorities. If our third-party manufacturers including any we contract with in the future, cannot successfully manufacture material that conforms to our specifications and the strict regulatory requirements of the FDA or others, they will not be able to secure or maintain regulatory approval for their manufacturing facilities. If the FDA or a comparable foreign regulatory authority does not approve the facility of a third-party manufacturer for the manufacture of TPOXX®, or if it withdraws any such approval in the future, it may significantly impact our ability to commercialize TPOXX®.

For example, Patheon, the manufacturer for IV TPOXX®, notified us that it will be closing the manufacturing line on which it manufactures IV TPOXX® in 2026. We have contracted with an alternative third-party manufacturer and are in the process of transferring the manufacturing process for IV TPOXX® to such third party. This manufacturing process is complex, and it may take significant time and resources to complete the transfer. In addition, upon completion, the third-party’s manufacturing facility will need to obtain FDA approval for the manufacture of IV TPOXX®. Failure to timely complete the transfer of the manufacturing process or to obtain FDA approval for the third-party manufacturing facility could hinder our ability to meet contractual obligations for IV TPOXX® and could cause material adverse consequences for our business.

If third parties on whom we rely for packaging and delivery of our products, are unable to meet the target timing for deliveries to our customers, product revenue recognition may be delayed and our business could suffer.

Additionally, we rely on third-party providers for storing, packaging and delivering certain of our products, including a portion of the stockpile of IV TPOXX® purchased by government under the 19C BARDA Contract that we manage, thereby entrusting such vendor or vendors with the care and handling of a substantial portion of IV TPOXX® inventory. Relying on third parties for storage, packaging and delivery of our products exposes us to risks, including reduced control over timing for delivery and quality assurance. If these third parties experience delays, capacity constraints, quality control problems or other disruptions to their operations, including due to supply chain shortages, natural disasters, health emergencies, pandemics, epidemics, civil unrest, labor disputes, cyber events, trade disputes or other trade barriers, international conflicts or global hostilities, our ability to ship products to our customers could be impaired and we may fail to meet our requirements for timely delivery. Failure to meet our scheduled product deliveries to our customers could cause the loss of sales, delayed revenue recognition or an increase in our costs, which could adversely affect our business, financial condition and results of operations.

If third parties do not manufacture our drug candidates or products in sufficient quantities and at an acceptable cost or in compliance with regulatory or contractual requirements and specifications, the fulfillment of contractual requirements under the 19C BARDA Contract, or any other procurement contract, or the development of our drug candidates could be delayed, prevented or impaired.

If our contract manufacturers are unable to generate enough materials to meet commercial obligations or satisfy clinical needs, the success of drug products may be jeopardized. Our current and anticipated future dependence upon others for the manufacture of our drug candidates may adversely affect our ability to develop drug candidates and perform on commercial contracts on a timely and competitive basis. If our third-party manufacturers’ production processes malfunction or contaminate our drug supplies during manufacturing, we may incur significant inventory loss that may not be covered by our contractual provisions or insurance policies.

We currently rely on third parties to demonstrate regulatory compliance, for regulatory and science support and for quality assurance with respect to the drug candidates manufactured for us. We intend to continue to rely on these third parties for these purposes with respect to production of commercial supplies of drugs that we successfully develop. Manufacturers are subject to ongoing, periodic, unannounced inspection by the FDA and corresponding state and foreign agencies or their designees to ensure strict compliance with applicable laws and regulations.

We cannot be certain that our present or future manufacturers will be able to comply with these regulations and other FDA regulatory requirements or similar regulatory requirements outside the U.S. Our government contracts and grants call for compliance with all applicable legal and regulatory requirements, however, we do not control third-party manufacturers and their methods for ensuring adherence to regulatory and legal standards. If we or these third parties fail to comply with applicable regulations, sanctions could be imposed on us which could significantly delay and adversely affect supplies of our drug candidates.

Table of Contents

Problems related to large-scale commercial manufacturing could cause an increase in costs or shortages of products or a delay in product launches.

Manufacturing API and finished drug products, especially in large quantities, is complex. Our products require several manufacturing steps at multiple facilities and involve complex techniques to assure quality and sufficient quantity. Our products must be made consistently and in compliance with a clearly defined manufacturing process. Accordingly, it is essential to be able to validate and control the manufacturing process to assure that it is reproducible. Slight deviations anywhere in the manufacturing process, including obtaining materials, filling, labeling, packaging, storage, shipping, quality control and testing, some of which all pharmaceutical companies, including us, experience from time to time, may result in lot failures, delay in the release of lots, product recalls or spoilage. Success rates can vary dramatically at different stages of the manufacturing process, which can lower yields and increase costs. We may experience deviations in the manufacturing process that may take significant time and resources to resolve and, if unresolved, may affect manufacturing output and/or cause us to fail to satisfy contractual commitments, lead to delays in our clinical trials or result in litigation or regulatory action. Such actions would hinder our ability to meet contractual obligations and could cause material adverse consequences for our business.

Risks Related to Product Development

Growth of our business may be impacted significantly by our success in completing development and commercialization of drug candidates, new formulations or additional indications for TPOXX®. If we are unable to commercialize new drug candidates, new formulations, or additional indications, or experience significant delays in doing so, our business may be materially harmed.

We have invested a substantial amount of our efforts and financial resources in the development of our drug candidates. Our ability to generate near-term cash flows is primarily dependent on the success of our smallpox antiviral drug TPOXX®, which has been approved by the FDA in oral and intravenous forms and by select international regulatory agencies in the oral form. The commercial success of our current and future drug candidates, new formulations or additional indications for TPOXX®, will depend on many factors, including:

• successful development of animal models;

• successful completion of clinical trials;

We may rely on FDA regulations known as the “Animal Rule” to obtain approval for most of our biodefense drug candidates. The Animal Rule permits the use of animal efficacy studies together with human clinical safety trials to support an application for marketing approval. These regulations are relied upon only occasionally. It is possible that results from these animal efficacy studies may not be predictive of the actual efficacy of our drug candidates in humans. If we are not successful in completing the development and commercialization of our drug candidates, whether due to our efforts or due to concerns raised by our governmental regulators or customers, our business could be materially adversely affected.

Table of Contents

We may not be able to fully commercialize the liquid suspension/pediatric formulation of TPOXX®, or additional indications for TPOXX®, if our clinical trials do not demonstrate adequate safety or our animal studies do not demonstrate adequate efficacy.

Before obtaining regulatory approval for the sale of our drug candidates, extensive development is required. The development of a smallpox treatment candidate requires clinical trials to demonstrate safety and animal studies to demonstrate efficacy. Clinical trials and animal studies, and related work, are resource-intensive, difficult to design and implement, can take many years to complete and are uncertain as to outcome. Success in pre-clinical testing and early clinical trials does not ensure that later clinical trials or animal efficacy studies will be successful, and interim results of a clinical trial or animal efficacy study do not necessarily predict final results.

A failure of one or more of our clinical trials or animal efficacy studies can occur at any stage of development. We may experience numerous unforeseen events during, or as a result of, pre-clinical testing and the clinical trial or animal efficacy study process that could delay or prevent our ability to receive regulatory approval or commercialize our drug candidates, including:

Liquid Suspension/Pediatric TPOXX® formulations are currently in product development and there can be no assurance of successful development or ultimate commercialization.

The fact that the FDA has approved the oral and IV formulations of TPOXX® does not guarantee that our approach to drug development will be effective or will result in the successful commercialization of the liquid suspension/pediatric formulation of TPOXX®, any new indication such as post-exposure prophylaxis, of TPOXX® or any other drug we seek to develop. We cannot predict with certainty whether any other drug candidate or expanded indication resulting from our research and development efforts will be approved by the FDA.

All of our potential drug candidates are prone to the risks of failure inherent in pharmaceutical product development, including the possibility that our drug candidates will not or cannot:

• be shown to be safe, non-toxic and effective;

• otherwise meet applicable regulatory standards;

• receive the necessary regulatory approvals;

• develop into commercially viable drugs;

• be manufactured or produced economically and on a large scale;

• be successfully marketed;

• achieve customer acceptance.

Table of Contents

In addition, third parties may seek to preclude us from marketing our drugs through enforcement of their proprietary or intellectual property rights that we are not aware of, or third parties may succeed in marketing equivalent or superior drug products that do not infringe our intellectual property. Our failure to develop safe, commercially viable future drug candidates or obtain approval for expanded indications and formulations of TPOXX® could have a material adverse effect on our ability to grow our business, and impair our financial condition and operations.

Risks Related to Our Intellectual Property

Our ability to compete may decrease if we do not adequately protect our intellectual property rights.

Our commercial success will depend in part on our ability to obtain and maintain regulatory exclusivity, patent and other intellectual property protection for our proprietary technologies, drug targets and potential products and to preserve our trade secrets and trademark rights. Because of the substantial length of time and expense associated with bringing potential products through the development and regulatory clearance processes to reach the marketplace, the pharmaceutical industry places considerable importance on obtaining regulatory, patent and trade secret protection. The patent positions of pharmaceutical and biotechnology companies can be highly uncertain and involve complex legal and factual questions. No consistent policy regarding the breadth of claims allowed in biotechnology patents worldwide has emerged to date. Accordingly, we cannot definitively predict the type and breadth of claims allowed in patents covering our products.

SIGA exclusively owns its key patent portfolios, which relate to its leading drug product, TPOXX® (also known as ST-246, tecovirimat). As of February 20, 2026, the TPOXX® patent portfolio has seven patent families consisting of 26 U.S. utility patents, 101 issued foreign patents, one U.S. utility patent application, and 12 foreign patent applications.

We also rely on trade secrets, know-how, continuing technological innovation and licensing opportunities. In an effort to maintain the confidentiality and ownership of trade secrets and proprietary information, we require our employees, consultants and some collaborators to execute confidentiality and invention assignment agreements upon commencement of a relationship with us. These agreements may not provide meaningful protection for our trade secrets, confidential information or inventions in the event of unauthorized use or disclosure of such information, and adequate remedies may not exist in the event of such unauthorized use or disclosure.

If our technologies are alleged or found to infringe the patents or proprietary rights of others, we may be sued, we may have to pay damages or be barred from pursuing a technology, or we may have to license those rights from and pay royalties to others on unfavorable terms. If we are sued, even if we prevail, such litigation may be costly.

Our commercial success will depend significantly on our ability to operate without infringing the patents or proprietary rights of third parties. Our technologies, or the technologies of third parties on which we may depend, may infringe the patents or proprietary rights of others. If there is an adverse outcome in any dispute concerning rights to these technologies, then we could be subject to significant liability, required to license disputed rights from or to other parties and/or required to cease using a technology necessary to carry out our research, development and commercialization activities. We do not currently license any patent rights from third parties relative to TPOXX®.

If our patents are challenged and found to be invalid or unenforceable, the value of our products could be harmed, and we could be subject to competition earlier than we anticipated.

The costs to establish or defend against claims of infringement or interference with patents or other proprietary rights can be expensive, distracting and time-consuming, even if the outcome is favorable. An outcome of any patent or proprietary rights administrative proceeding or litigation that is unfavorable to us may cause us to incur significant costs, and have a material adverse effect on us. Additionally, we may not prevail in any such action and such litigation often takes years to resolve creating business uncertainty if we are not able to resolve it quickly.

Furthermore, like many biopharmaceutical companies, we may from time to time hire scientific personnel formerly employed by other companies involved in one or more areas similar to the activities conducted by us. It is possible that we and/or these individuals may be subject to allegations of trade secret misappropriation or other similar claims as a result of their prior affiliations.

Risks Related to Our Common Stock

Affiliates of MacAndrews & Forbes Incorporated (together with its affiliates “MacAndrews”) have substantial ownership of SIGA stock and their interests may differ from the interests of other stockholders.

MacAndrews holds, directly or indirectly, approximately 34% of outstanding shares of SIGA stock. Due to MacAndrews’ substantial ownership percentage and the rights under the securities purchase agreement (the "Securities Purchase Agreement") that was signed in 2003 between SIGA and an affiliate of MacAndrews, MacAndrews has a level of influence over us and our subsidiaries that other investors do not have.

The concentration of ownership and voting power of MacAndrews will limit other stockholders’ ability to influence corporate matters and may also delay, defer or even prevent an acquisition by a third party or other change of control of our company and may make some transactions more difficult or impossible without the support of MacAndrews. Also, the concentration of voting power with MacAndrews could result in actions by the Company with which other stockholders do not agree.

Table of Contents

A future issuance of preferred stock may adversely affect the rights of the holders of our common stock.

Our certificate of incorporation allows our Board of Directors (the "Board") to issue up to 20,000,000 shares of preferred stock and to fix the voting powers, designations, preferences, rights and qualifications, limitations or restrictions of these shares without any further vote or action by the stockholders. The rights of the holders of common stock will be subject to, and could be adversely affected by, the rights of the holders of any preferred stock that we may issue in the future. The issuance of preferred stock could have the effect of making it more difficult for a third party to acquire a majority of our outstanding voting stock, thereby delaying, deferring or preventing a change of control.

General Risk Factors

Global infectious disease outbreaks, such as the COVID-19 pandemic, or climate-related matters could negatively impact the global economy on a broad scale and our business in particular.

The COVID-19 pandemic caused significant societal and economic disruption. The direct and indirect impacts of the pandemic were significant and broad-based, including supply chain disruptions and labor shortages that started during the pandemic and continue to represent business and financial risks. As such, the Company is continually coordinating with service providers and vendors, in particular third party contract manufacturing organizations that constitute our supply chain, with respect to risks and mitigating actions.

While the Company has not identified or been notified by government customers of impediments to the continued full performance of their government contracts, future global infectious disease outbreaks or climate-related matters could have material adverse impact on the financial condition of the Company and its long-term operating performance.

Future acquisitions, strategic investments, partnerships or alliances could be difficult to identify and integrate, divert the attention of management, disrupt our business, dilute stockholder value, materially change the risk profile of the Company and/or adversely affect our operating results and financial condition.

We may in the future seek to acquire or invest in businesses, products or technologies that we believe could complement or expand our services, enhance our technical capabilities or otherwise offer growth opportunities. The pursuit of potential acquisitions may divert the attention of management and cause us to incur various expenses in identifying, investigating and pursuing businesses. In addition, we may not be able to find and identify desirable acquisition targets or be successful in entering into an agreement with any particular target or consummating any such agreement. Even if we do consummate an acquisition, in connection therewith we may be required to issue equity (thereby diluting our current stockholders) or debt, we may not be able to integrate successfully the acquired personnel, operations and technologies, or effectively manage the combined business following the acquisition, or the acquired business could otherwise fail to meet our expectations, which, in each case, could have a material adverse effect on our business projections, financial condition, results of operations and prospects.

Table of Contents

The health security markets in which we compete and will compete are highly competitive.

The health security industry is characterized by rapid and significant technological change. Our success will depend on our ability to develop and apply our technologies in the design and development of our product candidates, to establish and maintain a market for our product candidates, and maintain and grow our market for TPOXX®. In addition, there are many companies, both public and private, including major pharmaceutical and chemical companies, specialized biotechnology firms, universities and other research institutions engaged in developing pharmaceutical, health security and biotechnology products. Many of these companies have substantially greater financial, technical, research and development resources, and human resources than us. Competitors may develop products or other technologies that are more effective than TPOXX® or than any products being developed by us, or may obtain FDA approval for products more rapidly than us. Following product approval and commercial launch, such as for TPOXX®, we still must compete in the manufacturing and marketing of such products, areas in which it is very difficult to succeed and in which we are partially dependent on third parties. Many potential competitors have manufacturing facilities and substantial marketing capabilities that may enable such companies to market competing products through existing channels of distribution which could provide a substantial advantage.

Product liability lawsuits could cause us to incur liabilities, which could be substantial, and require us to limit commercialization of any products that we may develop.

Like all pharmaceutical companies, we face an inherent business risk related to the sale of TPOXX® and any other products that we successfully develop and the testing of our product candidates in clinical trials. TPOXX® is currently identified as a covered countermeasure under the PREP Act declaration issued in October 2008, as amended, which provides us with substantial immunity with respect to the manufacture, administration or use of TPOXX®. Under the 19C BARDA Contract, the U.S. Government should indemnify us against claims by third parties for death, personal injury and other damages related to TPOXX®, including reasonable litigation and settlement costs, to the extent that the claim or loss results from specified risks not covered by insurance or caused by our grossly negligent or criminal behavior. There is no assurance that any future U.S. Government contracts will include a comparable indemnification provision. In addition, the collection process under the PREP Act can be lengthy and complicated, and there is no guarantee that we would be able to recover these indemnifiable amounts from the U.S. Government.

If we cannot successfully defend ourselves against future claims that our product or product candidates caused injuries and we are not entitled to or able to obtain indemnity by the U.S. Government with respect to such claims, or if the U.S. Government does not honor its indemnification obligations, we may incur liabilities, which could be substantial. Regardless of merit or eventual outcome, product liability claims may result in decreased demand for any product candidate or product that we may develop; withdrawal of a product from the market; costs and management time and focus to defend the related litigation; substantial monetary awards to trial participants or patients; loss of revenue; harm to our reputation; the inability to commercialize any products that we may develop. Additionally, a successful product liability claim or series of claims brought against us could cause our stock price to fall, could decrease our financial resources and materially exhaust our existing insurance or limit our ability to obtain insurance going forward, all of which would materially adversely affect our business and financial position.

We currently have product liability insurance with coverage we believe is adequate to protect against potential product liability claims. Product liability insurance is difficult to obtain and increasingly expensive. Should we face claims, we may not be able to maintain insurance coverage at a reasonable cost and we may not be able to maintain or obtain insurance coverage that will be adequate to satisfy any liability that may arise.

Our activities may involve hazardous materials, use of which may subject us to environmental regulatory liabilities.

Our biopharmaceutical research and development sometimes may involve the use of hazardous and radioactive materials and generation of biological waste. We are subject to federal, state and local laws and regulations governing the use, manufacture, storage, handling and disposal of these materials and certain waste products, and may have to incur significant costs to comply with current or future environmental laws and regulations. Although we believe that our CMOs’ safety procedures for handling and disposing of these materials comply with legally prescribed standards, the risk of accidental contamination or injury from these materials cannot be completely eliminated. In the event of an accident, we could be held liable for damages, and this liability could exceed our resources. We use through third parties, for example, small amounts of radioactive isotopes commonly used in pharmaceutical research, which are stored, used and disposed of in accordance with Nuclear Regulatory Commission regulations. Our general liability policy provides coverage up to annual aggregate limits of $2 million and coverage of $1 million per occurrence.

Table of Contents

The loss of key personnel or our ability to recruit or retain qualified personnel could adversely affect our results of operations.

We rely upon the ability, expertise, judgment, discretion, integrity and good faith of our senior management team, including our Chief Executive Officer, Chief Scientific Officer, Chief Financial Officer, and other key employees. Our success is dependent upon our personnel and our ability to recruit, retain and train high quality employees. We must continue to recruit, retain and motivate management and other employees sufficient to maintain our current business and support our projected growth. The loss of services of any members of our key management team could have a material adverse effect on our business.

Our business and operations would suffer in the event of a significant computer system failure, cyber-attack or deficiency in our cyber-security.

Despite the implementation of security measures, our internal computer systems, and those of third parties on which we rely, we are vulnerable to damage from computer viruses, malware, natural disasters, terrorism, war, telecommunication and electrical failures, cyber-attacks or cyber-intrusions over the Internet, phishing attacks, persons inside our organization or persons with access to systems inside our organization. The risk of a security breach or disruption, particularly through cyber-attacks or cyber-intrusion, including by computer hackers, foreign governments and cyber terrorists, has generally increased as the number, intensity and sophistication of attempted attacks and intrusions from around the world have increased and been targeted at pharmaceutical companies in particular. In addition, the increasing use of artificial intelligence technologies, including by our employees and third-party service providers, may increase cybersecurity risks, including risks related to data exposure, misuse of confidential or sensitive information, and the growing sophistication of AI-enabled cyber-attacks. If such an event were to occur and cause interruptions in our operations, it could result in a material disruption of our drug development programs, manufacturing or quality systems, or other GxP-regulated activities. For example, the loss, corruption, or unavailability of clinical trial data, manufacturing data, or quality records - whether maintained by us or by third parties such as CROs or CDMOs - could result in delays in regulatory approval efforts and significantly increase our costs to recover or reproduce the data.

Also, our processing of sensitive information may subject us to data privacy and security obligations, and confidential patient and other personal or sensitive information may be compromised in a cyber-attack or cyber-intrusion. In the United States, federal, state, and local governments have enacted numerous data privacy and security laws, including data breach notification laws, personal data privacy laws, consumer protection laws and other similar laws (e.g., wiretapping laws). For example, the Health Insurance Portability and Accountability Act of 1996 imposes specific requirements relating to the privacy, security and transmission of individually identifiable health information. If we or the third parties on which we rely fail, or are perceived to have failed, to address or comply with data privacy and security obligations, we could face significant consequences. These consequences may include, but are not limited to, government enforcement actions, litigation, additional reporting requirements and/or oversight, bans on processing personal data, orders to destroy or not use personal data and imprisonment of Company officials.

To the extent that any disruption or security breach was to result in a loss of or damage to our data or applications, or inappropriate disclosure of confidential or proprietary information, we could incur material legal claims and liability, damage to our reputation, and the further development of our drug candidates could be delayed.

We may need additional funding, which may not be available to us, and which may force us to delay, reduce or limit proposed acquisitions or strategic investments or any of our non-government funded product development programs or commercial efforts.

Although we believe our current cash position is strong, we may require additional financing and, while we have raised funds through credit facilities and the issuance of new equity or the exercise of options or warrants in the past, there is no guarantee that we will continue to be successful in raising such funds should we need to seek to do so. If we are unable to raise additional funds, we could be forced to discontinue, cease or limit certain strategic transactions or operations and equity investors could experience significant or total losses of their investments. Our cash flows may fall short of our projections or be delayed, or our expenses may increase, including as a result of inflation or interest rate increases, which could result in our capital being consumed significantly faster than anticipated. If we are able to obtain additional financing through the sale of equity or convertible debt securities, such sales may contain terms, such as liquidation and other preferences that are not favorable to us or our stockholders. If we raise additional funds through collaboration and licensing arrangements with third parties, it may be necessary to relinquish valuable rights to our technologies or product candidates or grant licenses on terms that may not be favorable to us. Debt financing arrangements, if available, may require us to pledge certain assets or enter into covenants that could restrict our business activities or our ability to incur further indebtedness and may be at interest rates and contain other terms that are not favorable to our stockholders.

The cash and cash equivalents that we use to meet our cash needs, including working capital and operating expenses, are held in deposit or investment accounts at four financial institutions. If one or multiple financial institutions fail, our deposit or investment accounts could be adversely affected due to the loss of or delay in obtaining access to all or a portion of our uninsured funds.

The cash and cash equivalents that we use to meet our cash needs, including working capital and operating expenses, are held in deposit or investment accounts at four financial institutions. The balance held in these accounts regularly exceeds the Federal Deposit Insurance Corporation (“FDIC”), standard deposit insurance limit or similar government guarantee schemes, or in the case of investment accounts, is not insured. If one or multiple financial institutions in which we hold such funds fails or is subject to significant adverse conditions in the financial or credit markets, we could be subject to a risk of loss of all or a portion of such uninsured funds or be subject to a delay in accessing all or a portion of such uninsured funds. Any such loss or lack of access to these funds could adversely impact our short-term liquidity and ability to meet our operating expense obligations.

Table of Contents

Item 1B. Unresolved Staff Comments

None.

Item 1C. Cybersecurity

Risk Management and Strategy

We regularly assess risks from cybersecurity threats, including through periodic risk assessments aligned with recognized cybersecurity risk management frameworks, and monitor our information systems for potential vulnerabilities. These activities are integrated into our enterprise risk management program and are designed to identify, escalate, investigate, resolve, and recover from cybersecurity incidents in a timely manner. The Company’s Chief Information Officer is responsible for developing and implementing our information security program and reporting on cybersecurity matters to the Board. Our Chief Information Officer has over a decade of experience leading cybersecurity oversight, and others on our IT security team have cybersecurity experience and certifications. We view cybersecurity as a shared responsibility, and we periodically perform simulations and tabletop exercises at a management level and engage external resources and advisors as needed. All employees are required to complete regular cybersecurity training through online courses and simulated exercises.

We collaborate with third parties to assess the effectiveness of our cybersecurity prevention and response systems and processes. These include cybersecurity assessors, consultants, and other external cybersecurity experts to assist in the identification, verification, and validation of cybersecurity risks, as well as to support associated mitigation plans when necessary. We have developed a third-party cybersecurity risk management process that applies a risk-based approach to due diligence and oversight of external entities, including vendors and service providers with access to Company systems or sensitive data.

To date, risks from cybersecurity threats, including those resulting from any previous cybersecurity incidents, have not materially affected our Company, including our business strategy, results of operations, or financial condition. We do not believe that cybersecurity threats resulting from any previous cybersecurity incidents of which we are aware are reasonably likely to materially affect our Company. For more information about the cybersecurity risks we face, see the risk factor entitled “Our business and operations would suffer in the event of a significant computer system failure, cyber-attack or deficiency in our cyber-security” in Item 1A. Risk Factors.

Governance

The full Board receives updates periodically or as needed during the year from the Company’s Chief Information Officer and actively participates in discussions with management and amongst themselves regarding cybersecurity risks. Updates delivered to the full Board typically include discussion of management’s actions to identify and detect threats, as well as planned actions in the event of a response or recovery situation. These updates also typically include a review of any recent enhancements to the Company’s defenses and management’s progress on its cybersecurity, as well as reports on key performance indicators, test results and related remediation, and recent threats and how the Company is managing those threats.

Item 2.Properties

Our offices are located in New York, NY, and Corvallis, Oregon. In May 2017, we entered into a new 10-year lease with a related party to let 3,200 square feet in New York, NY to serve as our corporate headquarters. For more information about the lease, see Note 13. Related Party Transactions, to the consolidated financial statements.

In Corvallis, we lease approximately 10,276 square feet. Until its expiration on December 31, 2017, this facility was leased under an amended lease agreement signed in January 2007, and most recently changed through an addendum in April 2015. On November 3, 2017, we entered into a new lease for the same space which was scheduled to expire in December 2019. In the second quarter of 2019, we exercised the first renewal option which was scheduled to expire in December 2021. In the second quarter of 2021, we exercised the second renewal option, which extended the lease expiration date to December 31, 2024. In the second quarter of 2024, we entered into an additional addendum, which extended the lease expiration date to December 31, 2026.

Item 3.Legal Proceedings

From time to time, we may be involved in a variety of claims, suits, investigations and proceedings arising from the ordinary course of our business, collections claims, breach of contract claims, labor and employment claims, tax and other matters. Although such claims, suits, investigations and proceedings are inherently uncertain and their results cannot be predicted with certainty, we believe that the resolution of such current pending matters, if any, will not have a material adverse effect on our business, consolidated financial position, results of operations or cash flow. Regardless of the outcome, litigation can have an adverse impact on us because of legal costs, diversion of management resources and other factors.

Item 4.Mine Safety Disclosures

Not applicable.

Table of Contents

PART II

Item 5.Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

The Company's common stock trades on The Nasdaq Global Market under the symbol "SIGA."

There were 29 holders of record as of February 13, 2026. We believe that the number of beneficial owners of our common stock is substantially greater than the number of record holders, because a large portion of common stock is held in broker “street names.”

On April 8, 2025, the Board declared a special dividend of $0.60 per share on the common stock of the Company. The special dividend was paid on May 15, 2025 to shareholders of record at the close of business on April 29, 2025. Any future payments of dividends on our common stock will be determined by our Board and will depend on our business conditions, financial results and other factors our Board deems relevant.

The Company did not repurchase any equity securities during the fourth quarter ended December 31, 2025.

There were no unregistered sales of equity securities during the fiscal year ended December 31, 2025 that have not been previously disclosed in a quarterly report on Form 10-Q or a current report on Form 8-K.

Table of Contents

Performance Graph

The following line graph compares the cumulative total stockholder return through December 31, 2025, assuming reinvestment of dividends, by an investor who invested $100 on December 31, 2020 in each of (i) our common stock; (ii) the Nasdaq Composite; and (iii) the Nasdaq Biotech Composite.

Securities Authorized for Issuance Under Equity Compensation Plans

The information required by this item concerning securities authorized for issuance under equity compensation plans is set forth in Item 12, “Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters.”

Table of Contents

Item 6.[Reserved]

Not applicable.

Table of Contents

Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations

The following discussion should be read in conjunction with the consolidated financial statements and related notes included elsewhere in this report. Refer to Part II, Item 7 in our Annual Report on Form 10-K for the fiscal year ended December 31, 2024 (filed with the SEC on March 11, 2025) for additional discussion of our financial condition and results of operations for the year ended December 31, 2024, as well as our financial condition and results of operations for the year ended December 31, 2024 compared to the year ended December 31, 2023. In addition to historical information, the following discussion and other parts of this Annual Report contain forward-looking information that involves risks and uncertainties.

Overview

SIGA Technologies, Inc. (“SIGA” or the “Company”) is a commercial-stage pharmaceutical company. The Company sells its lead product, TPOXX® (“oral TPOXX®,” also known as "tecovirimat," "Tecovirimat SIGA," or "TEPOXX (tecovirimat)" in certain international markets), to the U.S. Government and international governments (including government affiliated entities). In certain international markets, the Company may sell TPOXX® through a distributor. Additionally, the Company sells the intravenous formulation of TPOXX® ("IV TPOXX®") to the U.S. Government.

TPOXX® is an antiviral drug for the treatment of human smallpox disease caused by variola virus. On July 13, 2018, the United States Food & Drug Administration (“FDA”) approved oral TPOXX® for the treatment of smallpox. The Company has been delivering oral TPOXX® to the U.S. Strategic National Stockpile ("Strategic Stockpile") since 2013.

On May 18, 2022 the FDA approved IV TPOXX® for the treatment of smallpox.

In addition to being approved by the FDA, oral TPOXX® (tecovirimat) has received regulatory approval from the European Medicines Agency ("EMA"), Health Canada, the Medicines and Healthcare Products Regulatory Agency ("MHRA") of the United Kingdom, and the Japanese Pharmaceuticals and Medical Devices Agency ("PMDA"). The EMA, MHRA and PMDA approved oral TPOXX® for the treatment of smallpox, monkeypox ("mpox"), cowpox, and vaccinia complications following vaccination against smallpox. Health Canada approved TPOXX® for the treatment of smallpox.

TPOXX® was authorized under “exceptional circumstances” by the EMA and the MHRA, under the brand name Tecovirimat-SIGA. These regulators granted marketing authorizations under “exceptional circumstances” because it was not possible to obtain complete efficacy and safety information about the product due to the rarity of smallpox and other orthopoxviruses and because ethical considerations prevented conducting the necessary clinical studies. The Tecovirimat-SIGA marketing authorizations under “exceptional circumstances” are subject to certain specific obligations to gather additional data post-approval to help confirm the product’s safety and efficacy. All “exceptional circumstances” marketing authorizations are subject to annual reassessments that consider whether data generated pursuant to the specific obligations continue to confirm its positive benefit-risk profile. These annual reassessments determine whether the product’s marketing authorization should be maintained, changed, suspended, or withdrawn based on its benefit-risk profile.

With respect to the regulatory approvals by the EMA, PMDA, MHRA and Health Canada, oral tecovirimat represents the same formulation approved by the FDA in July 2018 under the brand name TPOXX®.

In connection with a potential FDA label expansion of oral TPOXX® for an indication covering smallpox post-exposure prophylaxis (“PEP”), the Company has completed an immunogenicity trial and an expanded safety trial. The timing of a potential submission of a supplemental New Drug Application to the FDA (“Supplemental NDA”) for a smallpox PEP indication for oral TPOXX® will be based on the results of ongoing sample analyses from the immunogenicity trial; the Company is currently targeting a Supplemental NDA submission within the next twelve months.

Macroeconomic Environment

Future macroeconomic volatility, including changes to and uncertainty regarding tariffs and trade policies, could cause cost increases resulting in an adverse effect on the Company’s operating results. The Company’s supply chain was designed to lessen the impact of macroeconomic volatility such as through development of a U.S. domestic supply chain including U.S. production of API and finished product, and minimal reliance on ex-U.S. components for API and oral TPOXX®.

With respect to IV TPOXX®, tariff activity or other trading restrictions involving the U.S. and Europe may materially increase raw material costs for IV TPOXX® and, in turn, may materially increase IV TPOXX® overall manufacturing costs.

Table of Contents

Procurement Contracts with the U.S. Government

19C BARDA Contract

On September 10, 2018, the Company entered into a contract with the U.S. Biomedical Advanced Research and Development Authority ("BARDA") pursuant to which SIGA agreed to deliver up to 1,488,000 courses of oral TPOXX® to the Strategic Stockpile, and to manufacture and deliver to the Strategic Stockpile, or store as vendor-managed inventory, up to 212,000 courses of IV TPOXX®. In October 2023, the contract was modified so that a course of IV TPOXX® was redefined within the contract from being 14 vials to being 28 vials; as such, the 19C BARDA Contract currently specifies 106,000 courses of IV TPOXX® (for the same payment amount as originally specified). In addition to the delivery of TPOXX® courses, the contract includes funding from BARDA for a range of activities, including: advanced development of IV TPOXX®, post-marketing activities for oral and IV TPOXX®, development of a pediatric formulation, support for manufacturing activities, and procurement activities. On April 8, 2025, total payments contemplated under the contract with BARDA were increased by $14.3 million to add funding for activities supporting manufacturing. On June 3, 2025, total payments contemplated under the contract with BARDA were increased by $13.2 million in connection with the development of the pediatric formulation of TPOXX®. As of December 31, 2025, the contract with BARDA (as amended, modified, or supplemented from time to time, the "19C BARDA Contract") contemplates up to approximately $630 million of payments, of which approximately $79.2 million of payments are included within the base period of performance, approximately $545.2 million of payments are related to exercised options and up to approximately $5.6 million of payments are currently specified as unexercised options. BARDA may choose in its sole discretion when, or whether, to exercise any of the unexercised options. The period of performance for options is up to ten years from the date of entry into the 19C BARDA Contract and such options could be exercised at any time during the contract term.

The base period of performance specifies potential payments of approximately $79.2 million for the following activities: payments of approximately $11.1 million for the delivery of approximately 35,700 courses of oral TPOXX® to the Strategic Stockpile; payments of $8.0 million for the manufacture of 10,000 courses (as currently defined within the contract as being 28 vials) of final drug product of IV TPOXX® ("IV FDP"), of which $3.2 million of payments are related to the manufacture of bulk drug substance ("IV BDS") to be used in the manufacture of IV FDP; payments of approximately $59.5 million to fund reimbursed activities; and payments of approximately $0.6 million for supportive procurement activities. As of December 31, 2025, the Company had received $11.1 million for the delivery of approximately 35,700 courses of oral TPOXX® to the Strategic Stockpile, $3.2 million for the manufacture of IV BDS, $4.8 million for the delivery of IV FDP to the Strategic Stockpile and $31.2 million for other base period activities. IV BDS has been used for the manufacture of courses of IV FDP. The $3.2 million received for the completed manufacture of IV BDS had been recorded as deferred revenue as of December 31, 2021, but with the delivery of IV FDP to the Strategic Stockpile during 2022, $2.9 million was recognized as revenue. The remaining $0.3 million of deferred revenue was recognized in the second quarter of 2024 as the IV FDP containing such IV BDS was delivered to and accepted by the Strategic Stockpile.

The options that have been exercised as of December 31, 2025, provide for payments up to approximately $545.2 million. As of December 31, 2025, there are exercised options for the following activities: payments up to $450.2 million for the manufacture and delivery of up to 1.5 million courses of oral TPOXX®; payments up to $76.8 million for the manufacture of courses of IV FDP; payments of up to approximately $3.6 million to fund post-marketing activities for IV TPOXX®; and payments of up to $14.6 million for funding of post-marketing activities for oral TPOXX®. As of December 31, 2025, a cumulative total of $450.2 million of oral TPOXX® has been delivered to the Strategic Stockpile and accepted; a cumulative total of $61.4 million of IV BDS or IV FDP has been either set aside in inventory or delivered to the Strategic Stockpile and accepted (IV BDS that has been set aside has been recorded as deferred revenue and will be recognized as revenue when the IV BDS is manufactured as IV FDP and delivered); and the Company has been cumulatively reimbursed $10.9 million in connection with post-marketing activities for oral and IV TPOXX®.

Unexercised options specify potential payments up to approximately $5.6 million in total (if all such options are exercised), all of which relates to supportive activities that we currently do not expect to be required.

Table of Contents

The options related to IV TPOXX® were divided into two primary manufacturing steps. There were options related to the manufacture of bulk drug substance (“IV BDS Options”), and there were corresponding options (for the same number of IV courses) for the manufacture of final drug product (“IV FDP Options”). BARDA had the sole discretion to choose to exercise any, all, or none of these options. The 19C BARDA Contract included: three separate IV BDS Options, each providing for the bulk drug substance equivalent of 32,000 courses (as currently defined within the contract) of IV TPOXX®; and three separate IV FDP Options, each providing for 32,000 courses of final drug product of IV TPOXX®. BARDA had the sole discretion as to whether to simultaneously exercise IV BDS Options and IV FDP Options, or whether to exercise options at different points in time (or alternatively, to only exercise the IV BDS Option but not the IV FDP Option). To date, BARDA has exercised all three IV BDS options and all three IV FDP options. The Company estimates that sales of the IV formulation under this contract (under current terms), would have a gross margin (sales less cost of sales, as a percentage of sales) that is less than 40%.

U.S. Department of Defense Procurement Contracts

In 2024, the Company had sales of approximately $10 million with the U.S. Department of Defense ("DoD") (also known as the Department of War). Sales consisted mostly of delivery of oral TPOXX®, with a minor amount of IV TPOXX® delivered.

Over the past four years, the Company has received three procurement contracts from the DoD, totaling $28 million in value, mostly in connection with the manufacture and delivery of oral TPOXX®. All deliveries specified under these contracts have been fulfilled.

International Sales Activity

In the year ended December 31, 2025, the Company had international sales of $5.8 million consisting of a delivery of oral TPOXX® to one country. The Company was the counterparty to the contract under which these international sales were made.

In the year ended December 31, 2024, the Company had international sales of $23.0 million consisting of deliveries of oral TPOXX® to 13 countries. For international sales in the first and second quarters, Meridian Medical Technologies ("Meridian") was the counterparty to contracts under which the sales were made (see discussion and definition below regarding International Promotion Agreement). For international sales in the third and fourth quarters, the Company was the counterparty to the contracts under which the sales were made.

Since the initiation of international sales in 2020, the Company has cumulatively recorded $137 million of oral TPOXX® international revenues.

Table of Contents

International Promotion Agreement

Under the terms of the current International Promotion Agreement, which was amended on March 27, 2024, and effective June 1, 2024, and further amended on August 30, 2024, the Company has primary responsibility for the advertising, promotion and sale of oral TPOXX® in all geographic regions. Meridian has limited, non-exclusive rights to advertise, promote, offer for sale and sell oral TPOXX® in the European Economic Area, Australia, Japan, Switzerland, the United Kingdom and the Association of Southeast Asian Nations and its member states (collectively, the “Current Territory”). Meridian also performs non-promotional activities under specified contracts with third parties entered into prior to June 1, 2024, that provide for the sale of oral TPOXX® in the Current Territory. The International Promotion Agreement entitles Meridian to receive a fee equal to a high single digit percentage of collected proceeds (whether collected by Meridian or the Company), net of certain expenses, of sales of oral TPOXX® in the Current Territory in the field of use specified in the International Promotion Agreement. The International Promotion Agreement has a fixed term that expires on May 31, 2026, with no automatic renewal.

Under the terms of the original International Promotion Agreement ("Pre-amendment International Promotion Agreement"), which had an initial term that expired on May 31, 2024, Meridian had been granted exclusive rights to market, advertise, promote, offer for sale, or sell oral TPOXX® in a field of use specified in the International Promotion Agreement in all geographic regions except for the United States (the “Territory”), and Meridian agreed not to commercialize any competing product, as defined in the Pre-amendment International Promotion Agreement, in the specified field of use in the Territory. Under the Pre-amendment International Promotion Agreement, as well as the current International Promotion Agreement, SIGA has always retained ownership, intellectual property, distribution and supply rights and regulatory responsibilities in connection with TPOXX®, and, in the United States market, also retained sales and marketing rights with respect to oral TPOXX®. SIGA’s consent is required prior to the entry by Meridian into any sales arrangement pursuant to the International Promotion Agreement.

Sales to international customers pursuant to the Pre-amendment International Promotion Agreement were invoiced and collected by Meridian, and such collections were remitted, less Meridian's fees, to the Company under a quarterly process specified in the Pre-amendment International Promotion Agreement; and Meridian was entitled to a specified percentage of the collected proceeds of sales of oral TPOXX®, net of certain expenses, for calendar years in which customer collected amounts net of such expenses were less than or equal to a specified threshold, and to a higher specified percentage of such collected net proceeds for calendar years in which such net collected amounts exceeded the specified threshold. Subsequent to June 1, 2024, only specified procurement contracts for the Current Territory entered into prior to June 1, 2024, continue to involve Meridian invoicing and collecting proceeds, and retaining a fee pursuant to the International Promotion Agreement.

Mpox

In connection with the 2022 response to a global mpox outbreak, a series of observational and randomized, placebo-controlled clinical trials were initiated to assess the safety and efficacy of TPOXX® in participants with mpox. The purpose of these randomized clinical trials was to seek to collect data on the potential benefits of using TPOXX® as an antiviral treatment for active mpox disease. As of December 31, 2025, three of the randomized, placebo-controlled clinical trials reported topline results: a randomized, placebo-controlled clinical trial in the Democratic Republic of the Congo ("DRC") known as PALM 007 (Tecovirimat for Treatment of Monkeypox Virus - NCT05559099), which was funded and sponsored by the National Institutes of Health's (NIH) National Institute of Allergy and Infectious Diseases (NIAID); the Study of Tecovirimat for Human Mpox Virus (STOMP) clinical trial (NCT05534984), which was a randomized, placebo-controlled, double-blind study also sponsored and funded by NIAID to evaluate the safety and efficacy of tecovirimat for the treatment of people with laboratory-confirmed or presumptive mpox disease that included enrollees from Argentina, Brazil, Japan, Mexico, Peru, Thailand, and the United States; and the UNITY clinical trial (Assessment of the Efficacy and Safety of Tecovirimat in Patients With Monkeypox Virus Disease - NCT NCT05597735), which was funded and sponsored by ANRS-Emerging Infectious Diseases, which included enrollees from Switzerland, Brazil, and Argentina. The PALM 007 study did not meet its primary endpoint of a statistically significant improvement in time to lesion resolution within 28 days post-randomization for patients in the DRC with mpox who received TPOXX® compared to patients who received placebo. Some improvement versus placebo was observed in patients receiving TPOXX® whose symptoms began five days or fewer before randomization and patients with severe or grave disease, defined by the World Health Organization (WHO) as having 100 or more skin lesions, however the significance of these data has not been established. Similarly, in the STOMP study, tecovirimat did not meet its primary endpoint of a statistically significant improvement in time to lesion resolution for adults with mild to moderate mpox and a low risk of developing severe disease. Additional analyses of subgroups, secondary and exploratory endpoints is ongoing in each of these studies. Topline data from the UNITY study, which was presented at a medical conference, also showed that the study did not meet its primary endpoint of a statistically significant improvement in time to lesion resolution for patients with mpox who received TPOXX® compared to patients who received placebo. In all three studies, TPOXX® exhibited a safety profile comparable to placebo. These safety results are consistent with prior studies and further support the strong safety profile that has been observed with tecovirimat over the past 15 years.

Two other randomized clinical trials, Platinum-CAN (Canada) and EPOXI (EU), which were started in response to the global mpox outbreak, are closed to enrollment and expected to yield similar results, given the design similarities across these trials.

Table of Contents

Critical Accounting Estimate

The methods, estimates and judgments we use in applying our accounting policies have a significant impact on the results we report in our consolidated financial statements, which we discuss under the heading “Results of Operations” following this section of our Management’s Discussion and Analysis of Financial Condition and Results of Operations. Some of our accounting policies require us to make difficult and subjective judgments, often as a result of the need to make estimates of matters that are inherently uncertain. Our most critical accounting estimate is revenue recognition over time.

Revenue Recognition

We account for revenue in accordance with ASC Topic 606, Revenue from Contracts with Customers (“ASC 606”). The unit of account in ASC 606 is a performance obligation. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. Our performance obligations are satisfied over time as work progresses or at a point in time. Revenue connected with performance obligations related to product delivery and supportive services are recognized at a point in time. Revenue connected with performance obligations related to research and development and certain product supportive services are recognized over time.

Due to the nature of the work required to be performed on many of our performance obligations for which revenue is recognized over time, the estimation of total revenue and costs to satisfy the obligations may be complex, subject to many variables and requires significant judgment. The consideration associated with these types of performance obligations is considered variable. We estimate variable consideration as the most likely amount to which we expect to be entitled. We include estimated amounts in the transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur and when any uncertainty associated with variable consideration is resolved. Our estimates of variable consideration and determination of whether to include estimated amounts in the transaction price are based largely on an assessment of our historical and anticipated performance, external factors, trends and all other information (historical, current and forecasted) that is reasonably available to us.

Contracts are often modified to account for additional services to be performed. We consider contract modifications to exist when the modification either creates new enforceable rights and obligations, or changes existing enforceable rights and obligations. If the effect of a contract modification on the transaction price changes our measure of progress for the performance obligation to which it relates, the impact will be recognized in the period of modification as an adjustment to revenue (either as an increase in or a reduction of revenue) on a cumulative catch-up basis.

We have a process in which management reviews the progress and execution of our performance obligations. As part of this process, management reviews information including, but not limited to, any outstanding key contract matters, progress towards completion and the related program schedule, identified risks and opportunities and the related changes in estimates of revenues and costs. The risks and opportunities include management’s judgment about the ability and cost to achieve the schedule, technical requirements and other contract requirements. Management must make assumptions and estimates regarding labor productivity, the complexity of the work to be performed, customer behavior and execution by our subcontractors, among other variables.

Based on this analysis, any quarterly adjustments to revenues, research and development expenses and cost of sales and supportive services are recognized as necessary in the period they become known. Changes in estimates of revenues, research and development expenses and cost of sales and supportive services are recognized quarterly on a cumulative catch-up basis, which recognizes in the current period the cumulative effect of the changes on current and prior periods based on a performance obligation’s percentage of completion. A significant change in one or more of these estimates could affect the profitability of one or more of our performance obligations.

Recently Issued Accounting Pronouncements

For discussion regarding the impact of accounting standards that were recently issued but are not yet effective, on our consolidated financial statements, see Note 2, Summary of Significant Accounting Policies, to the consolidated financial statements.

Table of Contents

Results of Operations for the Years ended December 31, 2025 and 2024

Revenues from product sales and supportive services for the years ended December 31, 2025 and 2024 were $88.0 million and $133.3 million, respectively. Such revenues for the year ended December 31, 2025 include $53.3 million of oral TPOXX® sales and $25.8 million of IV TPOXX® sales to the U.S. Government under the 19C BARDA Contract; $5.8 million of oral TPOXX® sales to one international country and $3.1 million of supportive services. Such revenues for the year ended December 31, 2024 include $73.9 million of oral TPOXX® sales and $26.2 million of IV TPOXX® sales to the U.S. Government under the 19C BARDA Contract; $23.0 million related to international sales of oral TPOXX®; and approximately $10.1 million of oral TPOXX® sales to the DoD.

Revenues from research and development activities for the years ended December 31, 2025 and 2024, were $6.5 million and $5.4 million, respectively. The revenues for the years ended December 31, 2025 and 2024, were mostly earned in connection with performance of research and development activities under the 19C BARDA Contract. The increase of $1.1 million of revenue is primarily related to an increase in reimbursable activities under the 19C BARDA Contract.

Cost of sales and supportive services for the years ended December 31, 2025 and 2024 were $29.7 million and $31.3 million, respectively. Such costs in 2025 were primarily associated with the manufacture and delivery of courses of oral and IV TPOXX® to the U.S. Government under the 19C BARDA Contract. Such costs in 2024 were primarily associated with the manufacture and delivery of oral TPOXX® courses to the U.S. Government, DoD and various international customers as well as the manufacture and delivery of IV TPOXX® courses to the U.S. Government.

Selling, general and administrative expenses for the years ended December 31, 2025 and 2024 were $21.2 million and $25.1 million, respectively. The net decrease of approximately $3.9 million primarily reflects a decrease in international promotion fees related to a combination of the amendment to the International Promotion Agreement with Meridian and lower international activity in 2025, as well as lower professional service and consulting costs, in addition to lower compensation expense associated with the nonrecurrence in 2025 of certain one-time payments and equity grants that occurred in 2024 in connection with new hires. Such decreases are partially offset by an increase in business development costs.

Research and development expenses were $20.0 million for the year ended December 31, 2025, an increase of approximately $7.7 million from the $12.3 million incurred during the year ended December 31, 2024. The expense increase is primarily attributable to an increase in self-funded research and development activity, as well as higher expenses for the implementation of information technology enhancements, higher compensation expense in connection with an increase in headcount, and an increase in the usage of regulatory and related consultants.

Table of Contents

Other income, net for the years ended December 31, 2025 and 2024 was $6.7 million and $6.1 million, respectively. These amounts reflect interest income earned on cash and cash equivalents.

For the year ended December 31, 2025, we recognized a tax provision of $7.1 million on pre-tax income of $30.4 million. Our effective tax rate for the year ended December 31, 2025 was 23.4% and differs from the statutory rate of 21% primarily as a result of non-deductible executive compensation under IRC Section 162(m), and state and local taxes.

On July 4, 2025, President Trump signed H.R. 1, the “One Big Beautiful Bill Act” (“OBBBA”) into law. The OBBBA makes permanent many of the provisions previously enacted as part of the 2017 Tax Cut and Jobs Act that were set to expire at the end of 2025 and includes other changes to certain U.S. corporate tax provisions including (i) the restoration of immediate expensing for domestic research and development expenditures, (ii) the reinstatement of 100% bonus depreciation for qualified property and (iii) favorably modifying the section 163(j) interest limitation (similar to EBITDA). FASB Topic 740, “Income Taxes”, requires the tax effects of changes in tax laws or rates be recognized in the period in which the law is enacted. The enactment of the OBBBA did not have a material impact on the Company’s effective tax rate. We continue to evaluate the OBBBA and its requirements, but we do not expect a material impact on our financial consolidate statements.

For the year ended December 31, 2024, we recognized a tax provision of $16.9 million on pre-tax income of $76.1 million. Our effective tax rate for the year ended December 31, 2024 was 22.2% and differs from the statutory rate of 21% primarily as a result of non-deductible executive compensation under IRC Section 162(m), and state and local taxes.

Liquidity and Capital Resources

As of December 31, 2025, we had $155.0 million in cash and cash equivalents, compared with $155.4 million at December 31, 2024. We believe that our liquidity and capital resources will be sufficient to meet our anticipated requirements for at least the next twelve months from the issuance of these financial statements.

Operating Activities

We prepare our consolidated statement of cash flows using the indirect method. Under this method, we reconcile net income to cash flows from operating activities by adjusting net income for those items that impact net income but may not result in actual cash receipts or payments during the period. These reconciling items include but are not limited to stock-based compensation, deferred income taxes and gains and losses from various transactions and changes in the consolidated balance sheet for working capital from the beginning to the end of the period.

Net cash provided by operations for the years ended December 31, 2025 and 2024 was $43.5 million and $48.8 million, respectively. For the year ended December 31, 2025, net cash increase from operations is due to the receipt of approximately $105 million from sales of oral and IV TPOXX® to the U.S. Government and international customers, of which approximately $85 million relates to 2025 sales and the remainder to collection of accounts receivable on the December 31, 2024 balance sheet, as well as the receipt of investment income on cash and cash equivalents, was partially offset by the payment of approximately $8 million of income taxes as well as for the use of cash (net of research development revenues) for inventory and customary operating activities. For the year ended December 31, 2024, net cash increase from operations was due to the receipt of approximately $122.5 million from sales of oral and IV TPOXX® to the U.S. Government and international customers, of which approximately $102 million related to 2024 sales and the remainder to collection of accounts receivable on the December 31, 2023 balance sheet, partially offset by the payment of approximately $30 million of income taxes as well as the use of cash for customary operating activities.

Table of Contents

On December 31, 2025 and 2024, our accounts receivable balance was approximately $3.3 million and $21.2 million, respectively. Our accounts receivable balance as of December 31, 2025, which was fully received by the Company through the end of February 2026, is primarily related to revenues in connection with the 19C BARDA Contract. Our accounts receivable balance as of December 31, 2024 primarily reflected sales of oral TPOXX® to various international countries and the DoD.

Investing Activities

We used $355,009 and $42,450 for capital expenditures for the years ended December 31, 2025 and 2024, respectively. Capital expenditures in 2025 were made in connection with the purchase of equipment related to future IV TPOXX® manufacturing.

Financing Activities

Cash used in financing activities for the years ended December 31, 2025 and 2024 was $43.6 million and $43.5 million, respectively. For the year ended December 31, 2025, we paid a special dividend of approximately $43.1 million and spent approximately $0.4 million associated with the payment of tax obligations for employee common stock tendered. For the year ended December 31, 2024, we paid a special dividend of approximately $42.7 million and spent approximately $0.8 million associated with the payment of tax obligations for employee common stock tendered.

Future Cash Requirements

As of December 31, 2025, we have outstanding purchase orders associated with manufacturing obligations in the aggregate amount of approximately $10.1 million.

Table of Contents

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Our investment portfolio includes cash and cash equivalents. Our main investment objective is the preservation of investment capital. We believe that our investment policy is conservative, both in the duration of our investments and the credit quality of the investments we hold. We do not utilize derivative financial instruments, derivative commodity instruments or other market risk sensitive instruments, positions or transactions to manage exposure to interest rate changes. As such, we believe that the securities we hold are subject to market risk, changes in the financial standing of the issuer of such securities and our interest income is sensitive to changes in the general level of U.S. interest rates.

Table of Contents

Item 8. Financial Statements and Supplementary Data

Index to the Consolidated Financial Statements

Report of Independent Registered Public Accounting Firm (PCAOB ID 238) 45

Consolidated Balance Sheets 47

Consolidated Statements of Operations and Comprehensive Income 48

Consolidated Statements of Changes in Stockholders’ Equity 49

Consolidated Statements of Cash Flows 50

Notes to Consolidated Financial Statements 51

Table of Contents

Report of Independent Registered Public Accounting Firm

TotheBoard of Directors and Stockholders of SIGA Technologies, Inc.

Opinions on the Financial Statements and Internal Control over Financial Reporting

We have audited the accompanying consolidated balance sheets of SIGA Technologies, Inc. and its subsidiaries (the "Company") as of December 31, 2025 and 2024, and the related consolidated statements of operations and comprehensive income, of changes in stockholders’ equity and of cash flows for each of the three years in the period ended December 31, 2025, including the related notes (collectively referred to as the "consolidated financial statements"). We also have audited the Company's internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

In our opinion, the consolidated financial statements referred to above present fairly, in all material respects, the financial position of the Company as of December 31, 2025 and 2024, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2025 in conformity with accounting principles generally accepted in the United States of America. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2025, based on criteria established in Internal Control - Integrated Framework (2013) issued by the COSO.

Basis for Opinions

The Company's management is responsible for these consolidated financial statements, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in Management’s Report on Internal Control over Financial Reporting appearing under Item 9A. Our responsibility is to express opinions on the Company’s consolidated financial statements and on the Company's internal control over financial reporting based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.

Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the consolidated financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the consolidated financial statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.

Definition and Limitations of Internal Control over Financial Reporting

A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Critical Audit Matters

The critical audit matter communicated below is a matter arising from the current period audit of the consolidated financial statements that was communicated or required to be communicated to the audit committee and that (i) relates to accounts or disclosures that are material to the consolidated financial statements and (ii) involved our especially challenging, subjective, or complex judgments. The communication of critical audit matters does not alter in any way our opinion on the consolidated financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Table of Contents

Revenue Recognition

As described in Note 2 to the consolidated financial statements, the Company’s revenue was $94.6 million for the year ended December 31, 2025. The Company’s performance obligations are satisfied at a point in time or over time as work progresses. As disclosed by management, revenue connected with performance obligations related to product delivery and supportive services are recognized at a point in time. The Company’s revenue related to current research and development performance obligations as well as certain product supportive services are recognized over time, because the customer simultaneously receives and consumes the benefits provided by the services as the Company performs these services. Management recognizes revenue related to these services based on the progress toward complete satisfaction of the performance obligation and measures this progress under an input method, which is based on the Company’s cost incurred relative to total estimated costs.

The principal consideration for our determination that performing procedures relating to revenue recognition is a critical audit matter is a high degree of auditor effort in performing procedures related to the Company’s revenue recognition.

Addressing the matter involved performing procedures and evaluating audit evidence in connection with forming our overall opinion on the consolidated financial statements. These procedures included testing the effectiveness of controls relating to the revenue recognition process, including controls over the recording of revenue at the transaction price once the performance obligations are satisfied. These procedures also included, among others (i) testing the completeness, accuracy and occurrence of product sales and supportive services revenue recognized for a sample of revenue transactions by obtaining and inspecting source documents, such as contracts, invoices, shipping and delivery documents and subsequent cash receipts; (ii) for research and development revenue and certain product supportive services, testing management’s process for determining the estimated costs to completely satisfy each performance obligation for a sample of contracts by (a) comparing the underlying cost estimates to approved contracts or modifications; (b) comparing the underlying transaction price to original contracts or modifications; and (c) testing actual costs incurred and their eligibility for billing under the respective contracts; and (iii) confirming a sample of outstanding customer invoice balances as of December 31, 2025.

/s/ PricewaterhouseCoopers LLP

Florham Park, New Jersey

March 10, 2026

We have served as the Company’s auditor since 1997.

Table of Contents

SIGA TECHNOLOGIES, INC.

CONSOLIDATED BALANCE SHEETS

As of

ASSETS

Current assets

LIABILITIES AND STOCKHOLDERS' EQUITY

Current liabilities

Commitments and contingencies (Note 12)

Stockholders' equity

The accompanying notes are an integral part of these financial statements.

Table of Contents

SIGA TECHNOLOGIES, INC.

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME

For the Years Ended December 31

Revenues

Operating expenses

Diluted earnings per share $ 0.32 $ 0.82 $ 0.95

The accompanying notes are an integral part of these financial statements.

Table of Contents

SIGA TECHNOLOGIES, INC.

CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS’ EQUITY

For the Years Ended December 31, 2025, 2024 and 2023

Accumulated

Additional Other Total

Common Stock Paid-In Accumulated Comprehensive Stockholders’

Shares Amount Capital Deficit Income (Loss) Equity

Issuance of common stock upon exercise of stock options 8,672 — — — — —

Issuance of common stock upon vesting of RSUs 144,576 15 (15 ) — — —

Issuance of common stock 49,940 5 (5 ) — — —

Issuance of common stock upon vesting of RSUs 369,142 37 (37 ) — — —

Issuance of common stock upon vesting of RSUs 273,678 27 (27 ) — — —

The accompanying notes are an integral part of these financial statements.

Table of Contents

SIGA TECHNOLOGIES, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

For the Years Ended December 31

Cash flows from operating activities:

Changes in assets and liabilities:

Cash flows from investing activities:

Cash flows from financing activities:

Repurchase of common stock — — (11,072,511 )

Supplemental disclosure of cash flows information:

Non-cash lease right-of-use asset and associated liability $ — $ 462,686 $ —

Issuance of common stock $ — $ 417,000 $ —

Issuance of common stock upon cashless exercise $ — $ — $ 87,540

The accompanying notes are an integral part of these financial statements

Table of Contents

SIGA TECHNOLOGIES, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1.Organization and Basis of Presentation

Description of Business

TPOXX® is an antiviral drug for the treatment of human smallpox disease caused by variola virus. On July 13, 2018, the United States Food & Drug Administration (“FDA”) approved the oral formulation of TPOXX® for the treatment of smallpox. The Company has been delivering oral TPOXX® to the U.S. Strategic National Stockpile ("Strategic Stockpile") since 2013.

On May 18, 2022 the FDA approved IV TPOXX® for the treatment of smallpox.

In addition to being approved by the FDA, oral TPOXX® (tecovirimat) has received regulatory approval from the European Medicines Agency ("EMA"), Health Canada, the Medicines and Healthcare Products Regulatory Agency ("MHRA") of the United Kingdom, and most recently, in December 2024, the Japanese Pharmaceuticals and Medical Devices Agency ("PMDA"). The EMA, MHRA and PMDA approved oral TPOXX® for the treatment of smallpox, monkeypox ("mpox"), cowpox, and vaccinia complications following vaccination against smallpox. Health Canada approved TPOXX® for the treatment of smallpox.

On July 24, 2025, the EMA’s Committee for Medicinal Products for Human Use (CHMP) closed its third annual reassessment for Tecovirimat-SIGA and initiated a referral procedure for the product following questions over its effectiveness in the treatment of mpox. These questions were raised following receipt of results from certain non-SIGA sponsored clinical trials evaluating tecovirimat as a potential mpox treatment including the PALM007 and STOMP clinical trials. In the referral procedure, CHMP reviewed all available data on the safety and efficacy of Tecovirimat-SIGA for all its authorized indications in order to make a recommendation to the European Commission whether the marketing authorization should be maintained, modified, suspended or withdrawn. The CHMP is expected to meet in March to issue its recommendation. The Company expects the CHMP will confirm the positive benefit-risk balance of Tecovirimat-SIGA as a treatment for smallpox, cowpox, and vaccinia complications, and maintain those indications in the product label. Regarding mpox, based on the results of the mpox clinical trials, the Company expects the CHMP will recommend withdrawal of the mpox indication. In the UK, Tecovirimat-SIGA is undergoing an annual reassessment by the MHRA. This reassessment, which is ongoing, is substantially similar to the EMA’s annual reassessment process and could result in a similar outcome.

With respect to the regulatory approvals by the EMA, PMDA, MHRA and Health Canada, oral tecovirimat represents the same formulation approved by the FDA in July 2018 under the brand name TPOXX®.

2.Summary of Significant Accounting Policies

Use of Estimates

Management is required to make estimates and assumptions that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the date of the financial statements and revenues and expenses during the periods reported. The most significant estimates are the variables used in the calculation of reported amounts of revenue recognized over time. Estimates and assumptions are reviewed periodically and the effects of revisions are reflected in the financial statements in the period they are determined to be necessary. Actual results could differ from these estimates.

Basis of Presentation and Consolidation

The accompanying consolidated financial statements include the accounts of SIGA Technologies, Inc. and its wholly owned subsidiaries. All inter-company accounts and transactions have been eliminated in consolidation. The consolidated financial statements and related disclosures are presented in accordance with generally accepted accounting principles in the United States of America (“US GAAP”) and reflect the consolidated financial position, results of operations and cash flows for all periods presented.

Table of Contents

Reclassifications

Certain reclassifications have been made to prior year amounts to conform to the current year's presentation.

Cash Equivalents

The Company considers all highly liquid investments with original maturities of three months or less to be cash equivalents.

Concentration of Credit Risk

The Company has cash in bank accounts that exceeds the Federal Deposit Insurance Corporation insured limits. The Company has not experienced any losses on its cash accounts and no allowance has been provided for potential credit losses because management believes the potential for losses is remote.

For sales in certain international jurisdictions, collection of certain receivables from international government sales would be coordinated through the International Promotion Agreement with Meridian Medical Technologies ("Meridian") (see Note 3), under which Meridian invoices and collects payments from international customers and remits such collections, less Meridian's fees, to the Company under a quarterly process specified in the International Promotion Agreement.

Accounts Receivable

Accounts receivable are recorded net of provisions for doubtful accounts. At December 31, 2025 and 2024, 75% and 45%, respectively, of accounts receivable represent receivables from the U.S. Government. An allowance for doubtful accounts is based on specific analysis of the receivables. At December 31, 2025 and 2024, the Company had no allowance for doubtful accounts.

Inventory

Inventory is stated at the lower of cost or net realizable value. The cost is determined using the first-in, first-out (FIFO) method. The Company capitalizes inventory costs associated with the Company’s products when, based on management’s judgment, future commercialization is considered probable and the future economic benefit is expected to be realized; otherwise, such costs are expensed as research and development. Inventory is evaluated for impairment periodically to identify inventory that may expire prior to expected sale or has a cost basis in excess of its net realizable value. If certain batches or units of product do not meet quality specifications or become obsolete due to expiration or inability to meet customer minimum shelf-life requirements, the Company records a charge to write down such unmarketable inventory to its net realizable value.

Property, Plant and Equipment

Aside from manufacturing equipment noted below, property, plant and equipment are stated at cost, net of accumulated depreciation. Depreciation and amortization are provided on a straight-line method over the estimated useful lives of the various asset classes. The estimated useful lives are as follows: five years for laboratory equipment; three years for computer equipment; and seven years for furniture and fixtures. Leasehold improvements are amortized over the shorter of the estimated useful lives of the assets or the lease term. Maintenance, repairs and minor replacements are charged to expense as incurred.

The Company purchased manufacturing equipment during Q32025. Depreciation on the manufacturing equipment will be calculated using the units of production method if and when the Company receives FDA approval for the associated manufacturing site.

Revenue Recognition

The Company accounts for revenue in accordance with ASC Topic 606,Revenue from Contracts with Customers (“ASC 606”).

Performance Obligations. A performance obligation is a promise in a contract to transfer a distinct good or service to the customer, and is the unit of account in ASC 606. A contract’s transaction price is allocated to each distinct performance obligation and recognized as revenue when, or as, the performance obligation is satisfied. As of December 31, 2025, the Company's active performance obligations, for the contracts outlined in Note 3, consist of the following: three performance obligations relate to research and development services; and one relates to manufacture and delivery of product.

Contract modifications may occur during the course of performance of our contracts. Contracts are often modified to account for changes in contract specifications or requirements. In most instances, contract modifications are for services that are not distinct, and, therefore, are accounted for as part of the existing contract.

The Company’s performance obligations are satisfied over time as work progresses or at a point in time. A portion of the Company’s revenue is derived from long-term contracts that span multiple years. All of the Company’s revenue related to current research and development performance obligations as well as certain product supportive services are recognized over time, because the customer simultaneously receives and consumes the benefits provided by the services as the Company performs these services. The Company recognizes revenue related to these services based on the progress toward complete satisfaction of the performance obligation and measures this progress under an input method, which is based on the Company’s cost incurred relative to total estimated costs. Under this method, progress is measured based on the cost of resources consumed (i.e., cost of third-party services performed, cost of direct labor hours incurred, and cost of materials consumed) compared to the total estimated costs to completely satisfy the performance obligation. Incurred costs represent work performed, which corresponds with, and thereby best depicts, the transfer of control to the customer. The incurred and estimated costs used in the measure of progress include third-party services performed, direct labor hours, and material consumed. The Company accounts for shipping and handling activities as fulfillment costs rather than as an additional promised service.

Table of Contents

Contract Estimates. Accounting for long-term contracts and grants involves the use of various techniques to estimate total contract revenue and costs.

Contract estimates are based on various assumptions to project the outcome of future events that often span multiple years. These assumptions include: labor productivity; the complexity of the work to be performed; external factors such as customer behavior and potential regulatory outcomes; and the performance of subcontractors, among other variables.

The nature of the work required to be performed on many of the Company’s performance obligations and the estimation of total revenue and cost at completion may be complex, subject to many variables and require significant judgment. The consideration associated with research and development services is variable as the total amount of services to be performed has not been finalized. The Company estimates variable consideration as the most likely amount to which it expects to be entitled. The Company includes estimated amounts in the transaction price to the extent it is probable that a significant reversal of cumulative revenue recognized will not occur and when any uncertainty associated with variable consideration is resolved. The Company’s estimates of variable consideration and determination of whether to include estimated amounts in the transaction price are based largely on an assessment of our historical and anticipated performance, external factors, trends and all other information (historical, current and forecasted) that is reasonably available to us.

A significant change in one or more of these estimates could affect the profitability of the Company’s contracts. As such, the Company reviews and updates its contract-related estimates regularly. The Company recognizes adjustments in estimated revenues, research and development expenses and cost of sales and supportive services under the cumulative catch-up method. Under this method, the impact of the adjustment on revenues, research and development expenses and cost of sales and supportive services recorded to date on a contract is recognized in the period the adjustment is identified.

Contract Balances. The timing of revenue recognition, billings and cash collections may result in billed accounts receivable, unbilled receivables (contract assets) and customer advances and deposits (contract liabilities) in the consolidated balance sheets. Generally, amounts are billed as work progresses in accordance with agreed-upon contractual terms either at periodic intervals (monthly) or upon achievement of contractual milestones. Under typical payment terms of fixed price arrangements, the customer pays the Company either performance-based payments or progress payments. For the Company’s cost-type arrangements, the customer generally pays the Company for its actual costs incurred, as well as its allocated overhead and G&A costs. Such payments occur within a short period of time from billing. When the Company receives consideration, or such consideration is unconditionally due, prior to transferring goods or services to the customer under the terms of a sales contract, the Company records deferred revenue, which represents a contract liability. During the year ended December 31, 2025, the Company recognized revenue of $10.7 million that was included in deferred revenue at the beginning of the period.

Remaining Performance Obligations. Remaining performance obligations represent the transaction price for which work has not been performed and excludes unexercised contract options. As of December 31, 2025, the aggregate amount of transaction price allocated to remaining performance obligations was $59.1 million. With respect to current obligations related to the manufacture and delivery of product, the Company expects such obligations to be mostly recognized as revenues within the next 12 months. With respect to the performance obligations related to research and development services, the Company expects such obligations to be recognized as revenue within the next three years as the specific timing for satisfying performance obligations is subjective and at times outside the Company's control.

Leases

The Company accounts for leases in accordance with ASC 842,Leases (“ASC 842”).

Table of Contents

The Company determines if an arrangement is a lease at inception. Leases with an initial term less than one year are not recorded on the balance sheet and the lease costs are recorded as an expense on a straight-line basis over the lease term. Operating leases with terms greater than one year result in a lease liability recorded in other liabilities with a corresponding right-of-use ("ROU") asset recorded in property, plant and equipment.

Operating lease liabilities are recognized at the commencement date based on the present value of future minimum lease payments over the lease term. ROU assets are recognized based on the corresponding lease liabilities adjusted for qualifying initial direct costs, prepaid or accrued lease payments and unamortized lease incentives. The Company has lease agreements with lease and non-lease components, which are accounted for as a single lease. Lease terms may include options to extend or terminate the lease which are incorporated into the Company's measurement when it is reasonably certain that the Company will exercise the option.

Research and Development

Research and development expenses include costs directly and indirectly attributable to the conduct of research and development programs, and performance pursuant to certain customer contracts, including employee related costs, materials, supplies, depreciation and maintenance of equipment, the cost of services provided by outside contractors, including services related to the Company’s clinical trials and facility costs, such as rent, utilities, and general support services. All costs associated with research and development are expensed as incurred. Costs related to the acquisition of technology rights, for which development work is still in process, and that have no alternative future uses, are expensed as incurred.

Goodwill

The Company evaluates goodwill for impairment at least annually or as circumstances warrant. The impairment review process compares the fair value of the reporting unit in which goodwill resides to its carrying value. The Company operates as one business and one reporting unit. Therefore, the goodwill impairment analysis is performed on the basis of the Company as a whole, using the market capitalization of the Company as an estimate of its fair value.

Share-based Compensation

The Company measures all stock-based awards granted to employees and directors based on the fair value on the date of the grant and recognizes the corresponding compensation expense of those awards over the requisite service period, which is generally the vesting period of the respective award. Over the past three years, the Company has issued stock options, restricted stock units (“RSU’s”) and performance or market condition share awards ("PSU’s"). Stock options and RSUs only have service-based vesting conditions, and the Company records the expense for these awards using the straight-line method. PSUs may have multiple tranches, each with certain performance conditions or market capitalization or stock price milestones and service-based vesting conditions. In the event a performance condition for a specific tranche is unknown, the Company will not consider the awards associated with that specific tranche granted until the performance condition is known. Once a performance condition is known for a PSU, the Company will record expense for these awards over the remaining service period once it is estimated that at least a portion of the performance condition will be met.

The fair value of each stock option grant is determined using the Black-Scholes option-pricing model, which uses as inputs the fair value of our common stock and assumptions we make for the volatility of its common stock, the expected term of the stock options, the risk-free interest rate for a period that approximates the expected term of the stock options and the expected dividend yield.

The fair value of RSU awards is determined by the value of our common stock and is recognized based on the portion of the requisite service period satisfied as of each valuation date. The fair valuation of the cash-settled awards changes based on changes in our common stock price. The portion of cash-settled RSUs that is recognized based on service period is reflected in accrued expenses and other current liabilities in our consolidated balance sheet. Increases (or decreases) in accrued expenses result in adjustments to earnings for the associated valuation updates.

The fair value of the PSUs is estimated based on the conditions of the award. Market based awards are valued using a Monte-Carlo valuation simulation through a third party. Similar to stock options, the Company makes assumptions for the volatility of its common stock, the expected term of the PSUs, the risk-free interest rate for a period that approximates the expected term of the PSUs and the expected dividend yield. The compensation expense for these types of PSUs is recognized using an accelerated amortization model. Performance based PSU awards, once the performance condition is known, are valued at each reporting period, and the amount of stock-based compensation expense is based on the probability of achievement against the pre-established performance measures and if necessary, a cumulative catch-up adjustment for expense is recorded to reflect any revised estimates regarding the probability of achievement.

Income Taxes

The Company recognizes income taxes utilizing the asset and liability method of accounting for income taxes. Under this method, deferred income taxes are recorded for temporary differences between financial statement carrying amounts and the tax basis of assets and liabilities at enacted tax rates expected to be in effect for the years in which the differences are expected to reverse. A valuation allowance is established if it is more likely than not that some or the entire deferred tax asset will not be realized. The recognition of a valuation allowance for deferred taxes requires management to make estimates and judgments about the Company’s future profitability which are inherently uncertain. The Company may recognize tax benefits from an uncertain tax position only if it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position. The tax benefits recognized in the financial statements from such position should be measured based on the largest benefit that has a greater than fifty percent likelihood of being realized upon ultimate settlement. The Company re-evaluates uncertain tax positions and considers factors, including, but not limited to, changes in tax law, the measurement of tax positions taken or expected to be taken on tax returns, and changes in circumstances related to a tax position. The Company recognizes interest and penalties related to income tax matters in income tax expense.

Table of Contents

Repurchase of shares

When shares recognized as equity are repurchased, the amount of the consideration paid, which includes directly attributable costs, is recognized as a deduction from equity. The excess of the purchase price above par value of repurchased shares that are retired is presented as an increase to accumulated deficit (or a reduction of retained earnings, if any).

Earnings (Loss) per Share

Basic earnings per share is computed by dividing net income (loss) by the weighted-average number of common shares outstanding during the period. Diluted earnings per share is computed by dividing net income (loss) by the weighted-average number of common shares outstanding during the period, assuming potentially dilutive common shares from option exercises, RSUs, and other incentives had been issued and any proceeds received in respect thereof were used to repurchase common stock at the average market price during the period. The assumed proceeds used to repurchase common stock is the sum of the amount to be paid to the Company upon exercise of options and the amount of compensation cost attributed to future services not yet recognized.

Fair Value of Financial Instruments

The carrying value of cash and cash equivalents, accounts receivable, accounts payable and accrued expenses and other current liabilities approximates fair value due to the relatively short maturity of these instruments.

The measurement of fair value requires the use of techniques based on observable and unobservable inputs. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect our market assumptions. The inputs create the following fair value hierarchy:

• Level 1 – Quoted prices for identical instruments in active markets.

There were no transfers between levels of the fair value hierarchy during 2025 or 2024. As of December 31, 2025 and December 31, 2024, the Company had approximately $55.8 million and $53.5 million, respectively, of cash equivalents classified as Level 1 financial instruments. There were no Level 2 or Level 3 financial instruments as of December 31, 2025 or December 31, 2024.

For the years ended December 31, 2025, 2024 and 2023, interest income of $6.7 million, $6.1 million and $4.2 million, respectively, was included in Other income, net on the Consolidated Statements of Operations and Comprehensive Income.

Loss Contingencies

The Company is subject to certain contingencies arising in the ordinary course of business. The Company records accruals for these contingencies to the extent that a loss is both probable and reasonably estimable. If some amount within a range of loss appears to be a better estimate than any other amount within the range, that amount is accrued. Alternatively, when no amount within a range of loss appears to be a better estimate than any other amount, the lowest amount in the range is accrued. The Company expenses legal costs associated with loss contingencies as incurred. We record anticipated recoveries under existing insurance contracts when recovery is assured.

Table of Contents

Segment Information

The Company is managed and operated as one business. The entire business is managed by a single management team that reports to the Chief Executive Officer, who is the Chief Operating Decision Maker ("CODM"). Refer to Note 11 for further information on the Company's reportable segment.

Recent Accounting Pronouncements

In December 2023, the FASB issued ASU No.2023-09, “Income Taxes (Topic 740): Improvements to Income Tax Disclosures” (“ASU 2023-09”). ASU 2023-09 requires more disaggregated income tax disclosures, including (i) the income tax rate reconciliation using both percentages and reporting currency amounts; (ii) specific categories within the income tax rate reconciliation; (iii) additional information for reconciling items that meet a quantitative threshold; (iv) the composition of state and local income taxes by jurisdiction; and (v) the amount of income taxes paid disaggregated by jurisdiction. ASU 2023-09 became effective for our fiscal year ending December 31, 2025 and the Company applied the amendments retrospectively to all prior periods presented in our consolidated financial statements. See Note 10 – Income Taxes.

In November 2024, the FASB issued ASU 2024-03,Income Statement-Reporting Comprehensive Income-Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses, requiring public entities to disclose additional information about specific expense categories in the notes to the consolidated financial statements on an interim and annual basis. ASU 2024-03 is effective for fiscal years beginning after December 15, 2026, and for interim periods beginning after December 15, 2027, with early adoption permitted. The Company is currently evaluating the impact of adopting ASU 2024-03.

3. Procurement Contracts and Research Agreements

19C BARDA Contract

On September 10, 2018, the Company entered into a contract with the U.S. Biomedical Advanced Research and Development Authority ("BARDA") pursuant to which SIGA agreed to deliver up to 1,488,000 courses of oral TPOXX® to the Strategic Stockpile, and to manufacture and deliver to the Strategic Stockpile, or store as vendor-managed inventory, up to 212,000 courses of IV TPOXX®. In October 2023, the contract was modified so that a course of IV TPOXX® was redefined within the contract from being 14 vials to being 28 vials; as such, the 19C BARDA Contract currently specifies 106,000 courses of IV TPOXX® (for the same payment amount as originally specified). In addition to the delivery of TPOXX® courses, the contract includes funding from BARDA for a range of activities, including: advanced development of IV TPOXX®, post-marketing activities for oral and IV TPOXX®, development of a pediatric formulation, support for manufacturing activities, and procurement activities. On April 8, 2025, total payments contemplated under the contract with BARDA were increased by $14.3 million to add funding for activities supporting manufacturing. On June 3, 2025, total payments contemplated under the contract with BARDA were increased by $13.2 million in connection with the development of the pediatric formulation of TPOXX®. As of December 31, 2025, the contract with BARDA (as amended, modified, or supplemented from time to time, the "19C BARDA Contract") contemplates up to approximately $630 million of payments, of which approximately $79.2 million of payments are included within the base period of performance, approximately $545.2 million of payments are related to exercised options, and up to approximately $5.6 million of payments are currently specified as unexercised options. BARDA may choose in its sole discretion when, or whether, to exercise any of the unexercised options. The period of performance for options is up to ten years from the date of entry into the 19C BARDA Contract and such options could be exercised at any time during the contract term.

Table of Contents

Revenues in connection with the 19C BARDA Contract are recognized either over time or at a point in time. Performance obligations related to product delivery generate revenue at a point in time. Revenue from other performance obligations under the 19C BARDA Contract are recognized over time using an input method using costs incurred to date relative to total estimated costs at completion. For the years ended December 31, 2025 and 2024, the Company recognized revenues of $9.6 million and $5.4 million, respectively, on an over time basis. In contrast, revenue recognized for product delivery and therefore at a point in time for the years ended December 31, 2025 and 2024, was $79.1 million and $100.1 million, respectively.

U.S. Department of Defense Procurement Contracts

Table of Contents

SIGA US Equity

SIGA · 10-K · period ended 2025-12-31

Item 1A. Risk Factors

Item 1B. Unresolved Staff Comments

Item 1C. Cybersecurity

Item 2.Properties

Item 3.Legal Proceedings

Item 4.Mine Safety Disclosures

Item 5.Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

Item 6.[Reserved]

Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Item 8. Financial Statements and Supplementary Data

SIGA US Equity☆

SIGA · 10-K · period ended 2025-12-31

Item 1A. Risk Factors

Item 1B. Unresolved Staff Comments

Item 1C. Cybersecurity

Item 2.Properties

Item 3.Legal Proceedings

Item 4.Mine Safety Disclosures

Item 5.Market for Registrant’s Common Equity, Related Stockholder Matters and Issuer Purchases of Equity Securities

Item 6.[Reserved]

Item 7.Management’s Discussion and Analysis of Financial Condition and Results of Operations

Item 7A. Quantitative and Qualitative Disclosures About Market Risk

Item 8. Financial Statements and Supplementary Data

SIGA US Equity