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

The Management’s Discussion and Analysis of Financial Condition and Results of Operations contains forward-looking statements regarding future events and our future results that are subject to the safe harbors created under the Securities Act of 1933 (the “Securities Act”) and the Securities Exchange Act of 1934 (the “Exchange Act”). All statements other than statements of historical facts are statements that could be deemed forward-looking statements. These statements are based on current expectations, estimates, forecasts and projections about the industry in which we operate and the beliefs and assumptions of our management. In some cases, forward-looking statements can be identified by the use of words such as “believe,” “could,” “expect,” “may,” “estimate,” “continue,” “anticipate,” “intend,”“should,” “plan,”“predict,” “will,” “would,” “project,” “potential,”or the negative thereof or other comparable terminology. In addition, any statements that refer to projections of our future financial performance, our anticipated growth and trends in our business and industry and other characterizations of future events or circumstances are forward-looking statements. Readers are cautioned that these forward-looking statements are only predictions and are subject to risks, uncertainties and assumptions that are difficult to predict, including those identified in the Risk Factors discussed in Item 1A, in the discussion below, as well as in other sections of this Annual Report on Form 10-K. Therefore, actual results may differ materially and adversely from those expressed in any forward-looking statements. All forward-looking statements and reasons why results may differ included in this report are made as of the date hereof, and we assume no obligation to update these forward-looking statements or reasons why actual results might differ.

Overview

We develop, market and sell platform, cloud and managed services, which are powered by agentic AI, that enable CSPs providers of all types and sizes to innovate and transform their businesses to focus on delivering outstanding subscriber experiences and become CXPs. The platform combines the Calix Agent WorkforceTM with intelligent appliances, software, cloud and fully integrated SmartLifeTM managed services to enable simplified business models that acquire, retain and grow subscribers and revenue. Calix Customer Success guides service providers through every stage of their transformation journey with expertise across technology, business and market insights. Our partner community extends innovation so customers can grow their businesses across markets at scale. With deep broadband expertise and an end-to-end approach from the datacenters’ access edge to every residential, business and municipal subscriber location, Calix enables any service provider to simplify operations, engagement, and service; innovate for their subscribers; and grow value for members, investors, and the communities they serve. This focus on subscriber experience allows CXPs to expand their brand through increased subscriber acquisition, loyalty and revenue while reducing their operating costs.

We market our platform, cloud and managed services to CSPs globally through our direct sales force as well as select resellers. Our customers range from smaller, regional service providers to some of the world’s largest service providers. We have approximately 1,600 active customers that have deployed passive optical, Active Ethernet or point-to-point Ethernet fiber access networks or our subscriber premise appliances.

Our revenue and potential revenue growth will depend on, among other things, our ability to develop, market and sell our platform and managed services to strategically aligned customers of all types such as MSPs, local and competitive exchange carriers, cable MSOs, WISPs, fiber overbuilders such as municipalities, electric cooperatives, tribal communities, multiple dwelling units (“MDU”) and hospitality providers in the U.S. and internationally. Our growth is also highly dependent on the speed and willingness of customers to adopt our platform and managed services.

Revenue fluctuations result from many factors, including, but not limited to: increases or decreases in customer orders for our products and services, global economic and geopolitical events and conditions, including tariffs, trade controls, inflation, economic downturns and market, financial or other factors such as government stimulus or shutdowns that may delay or materially impact customer purchasing decisions, non-availability of products due to supply chain challenges, including component and labor shortages and increasing lead times as well as disruptions as a result of pandemics or natural disasters, contractual terms with customers that result in delayed revenue recognition and varying budget cycles and seasonal buying patterns of our customers. More specifically, our customers have in the past spent less in the first quarter as they are finalizing their annual budgets, and in certain regions, customers are challenged by winter weather conditions that inhibit fiber deployment in outside infrastructure. Our revenue is also dependent upon our customers’ success in growing their subscribers, timing of purchases, capital expenditure plans and decisions to upgrade their networks or adopt new technologies, including adoption of our software and cloud platform solutions, as well as our ability to grow our customer base.

Cost of revenue is strongly correlated to revenue and tends to fluctuate due to all of the above factors that may cause revenue fluctuations. Factors that have impacted our cost of revenue, or that we expect may impact cost of revenue in future periods, also include: changes in the mix of products delivered, customer location and regional mix, changes in the cost of our inventory, investments to support expansion of cloud and customer support offerings as well as our customer success organization, changes in product warranty, incurrence of retrofit costs, amortization of intangibles, allowances for obligations to our suppliers and inventory write-downs. Factors that we expect may impact our cost of revenue in future periods include the

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same factors in the prior quarter, changes in trade policies and the transition from DDR4 to DDR5 memory. Regarding trade policies, in April 2025, the U.S. President signed an executive order increasing tariffs on imports from numerous countries, including China and other Asian countries where our sole-source or limited-source suppliers are located. Currently, the majority of our finished goods are exempt from tariffs. For imported components for domestic manufacturing and certain finished goods, these actions increased our cost of revenue. We continue to evaluate the actions we may be able to take to mitigate such costs as we monitor and navigate this challenging and dynamic operating environment. Regarding the DDR4 to DDR5 transition, the reduction in manufacturing capacity of DDR4 memory has resulted in increased DDR4 memory prices and will increase the cost of our products. In addition, we periodically ship by air versus by ocean in order to meet delivery commitments to our customers, which is more costly. Cost of revenue also includes fixed expenses related to our internal operations, which could increase our cost of revenue as a percentage of revenue if our revenue declines.

Our gross profit and gross margin fluctuate based on timing of factors such as changes in customer mix and changes in the mix of products demanded and sold (and any related write-downs of existing inventory or accrual for supplier commitments) and have in the past been and may be negatively impacted by increases in mix of revenue from channel sales rather than direct sales or other unfavorable customer or product mix, shipment volumes and any related volume discounts, changes in our product and services costs, pricing decreases or discounts, new product introductions or upgrades to existing products, customer rebates and incentive programs due to competitive pressure or materials shortages, supply constraints, investments to support expansion of cloud and customer support offerings, tariffs or unfavorable changes in trade policies.

Our operating expenses fluctuate based on the following factors among others: changes in headcount and personnel costs, which comprise a significant portion of our operating expenses; variable compensation due to fluctuations in shipment volumes or level of achievement against performance targets; timing of research and development expenses, including investments in innovative solutions and new customer segments, prototype builds and outsourced development resources; investments in marketing programs; asset write-offs; investments in our business and information technology infrastructure; and fluctuations in stock-based compensation expenses due to timing of equity grants or other factors affecting vesting.

Further, as a result of factors contributing to the fluctuations described above among other factors, many of which are outside our control, our quarterly operating results fluctuate from period to period. Comparing our operating results on a period-to-period basis may not be meaningful, and you should not rely on our past results as an indication of our future performance.

Critical Accounting Estimates

Our financial statements are prepared in accordance with U.S. generally accepted accounting principles. These accounting principles require us to make certain estimates and judgments that can affect the reported amounts of assets and liabilities as of the date of the financial statements, as well as the reported amounts of revenue, costs and expenses during the periods presented. We base our estimates, assumptions and judgments on historical experience and on various other factors that are believed to be reasonable under the circumstances. To the extent there are material differences between these estimates and actual results, our financial statements may be affected. We evaluate our estimates, assumptions and judgments on an ongoing basis.

We believe the following critical accounting policies affect our significant judgments and estimates used in the preparation of our financial statements.

Revenue Recognition

Revenue is recognized when a performance obligation is satisfied, which occurs when control of the promised goods or services is transferred to the customer, in an amount that reflects the consideration we expect to be entitled to in exchange for those goods or services. Revenue from sales of access and premises appliances is recognized when control is transferred to the customer, which is generally when the products are shipped. Revenue from software platform licenses, which provides the customer with a right to use the software as it exists, is generally recognized upfront when the license is made available to the customer. Revenue from cloud-based software subscriptions, customer support, maintenance, extended warranty subscriptions and managed services is generally recognized ratably over the contract term. Revenue from professional services and training is recognized as the services are delivered.

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. 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 hardware products contain both software and non-software components that function together to deliver the products’ essential functionality and therefore constitutes a single performance obligation as the promise to transfer the individual software and non-software components is not separately identifiable and, therefore, not distinct. Cloud-based software subscriptions can include multi-year agreements with a fixed annual fee for a minimum committed usage level. To the extent that minimum committed usage level each year varies, we have concluded that each year represents a distinct stand-ready performance obligation and the transaction price allocated to each performance obligation is recognized as revenue ratably over each annual period.

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Our contracts generally include multiple performance obligations. For such arrangements, we allocate the contract’s transaction price to each performance obligation using the relative stand-alone selling price of each distinct good or service in the contract. Observable prices of a product or service when we sell them separately based on stratification by classes of customers and products are the best estimate of stand-alone selling prices. However, when stand-alone selling prices are not directly observable, they are estimated, and judgment is required in their determination. In these instances, we determine stand-alone selling prices using all other available information, which may include pricing practices relative to geographies, market conditions, competitive landscape, characteristics of targeted customers for hardware products, internal costs and gross margin objectives for services and internal costs and value assessments for subscriptions.

Inventory Valuation and Supplier Purchase Commitments

Inventory, which primarily consists of finished goods purchased from CMs or ODMs, is stated at the lower of cost (determined by the first-in, first-out method) and net realizable value. Inbound shipping costs and tariffs are included in the cost of inventory. In addition, from time to time, we procure component inventory primarily due to the discontinuation of critical components by suppliers, a change in suppliers or in connection with our supply assurance plans. This component inventory is then consigned back to our suppliers to be consumed on future finished good builds.

We regularly monitor inventory on-hand and record write-downs for excess and obsolete inventory. We also evaluate our supplier purchase commitments and record a liability for excess and obsolete components consistent with the valuation of our excess and obsolete inventory and future production requirements. These write-downs and accruals are based on our assumptions of demand for our products and requires significant judgement of relevant factors including a comparison of the quantity and cost of inventory on hand to our estimated forecast of customer demand, current levels of orders and backlog, market conditions, potential obsolescence of technology, product life cycles and whether pricing trends or forecasts indicate that the carrying value of inventory exceeds our estimated selling price. Factors that could influence management’s assumptions and judgements include changes in economic conditions, competitive dynamics, losing a key customer, changes in our customers’ capital expenditures, government investment programs, technology changes, new product introductions and supply-chain lead times. Actual demand may differ from forecasted demand and may have a material effect on gross profit. If inventory is written down, a new cost basis is established that cannot be increased in future periods.

Recent Accounting Pronouncements Not Yet Adopted

In November 2024, the Financial Accounting Standards Board (“FASB”) issued Accounting Standard Update (“ASU”) No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures, which requires additional disclosure of certain costs and expenses within the notes to the financial statements. The updated standard is effective for our annual periods beginning in 2027 and interim periods beginning in the first quarter of 2028. Early adoption is permitted. We are currently evaluating the impact that the updated standard will have on our financial statement disclosures.

In September 2025, the FASB issued ASU No. 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software, which clarifies and modernizes the accounting for internal-use software. ASU No. 2025-06 is effective for us in the first quarter of 2028, with early adoption permitted. The standard permits application of the guidance using a prospective, retrospective, or modified transition approach. We are currently evaluating the impact that the updated standard will have on our financial statement disclosures.

There have been no other accounting pronouncements or changes in accounting pronouncements that are significant or potentially significant to us.

Results of Operations for Years Ended December 31, 2025 and 2024

Revenue

The following table sets forth our revenue (dollars in thousands):

Revenue:

Our revenue increased by $168.5 million, or 20%, during 2025 compared with 2024. The increase in appliance revenue was due to the adoption of our platform, cloud and managed services by new customers as we continue to take footprint from legacy box vendors and the continued robust expansion of our appliances within our existing customer base. The increase in software and service revenue is due to our CXP customers adding new subscribers. Our software is sold on a per-subscriber basis. CXPs use

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our platform, cloud and managed services to deliver better subscriber experiences as evidenced by best-in-class Net Promoter ScoresSM, thereby allowing them to take market share.

Our revenue is principally derived in the U.S., which represented 93% of revenue in 2025 and 92% in 2024. Our primary focus has been, and in the near term will continue to be, the U.S. and Canada given our large, direct sales and marketing presence and the amount of government stimulus being invested into underserved and not-served areas of these countries. With the introduction of our third-generation platform, we will increase our attention on international markets.

No customer accounted for more than 10% of our revenue for 2025, 2024 or 2023. See Note 11 “Revenue from Contracts with Customers” to the Consolidated Financial Statements included in this Annual Report on Form 10-K for more details on concentration of revenue for the years presented.

Gross Profit and Gross Margin

The following table sets forth our gross profit and gross margin (dollars in thousands):

Gross profit:

Gross margin:

Software and service 62.9 % 56.3 %

Gross profit increased by $114.7 million to $568.3 million during 2025 from $453.6 million during 2024. This increase was mainly due to the corresponding increase in revenue. Gross margin increased to 56.8% during 2025 from 54.6% during 2024. The increase in gross margin of 220 basis points, compared to the corresponding period in 2024, was primarily related to the continued adoption of our platform, cloud and managed services by new broadband service providers and our CXP customers winning new subscribers.

Operating Expenses

Sales and Marketing Expenses

Sales and marketing expenses consist of personnel costs, employee sales commissions, marketing programs and events, software tools and travel-related expenses. The following table sets forth our sales and marketing expenses (dollars in thousands):

Percent of revenue 25 % 26 %

Sales and marketing expenses increased by $30.8 million during 2025 compared to 2024 primarily due to increases in personnel expenses of $20.6 million, mostly related to incentive compensation and increased headcount, stock-based compensation of $9.9 million and travel expenses of $2.3 million. These increases were partially offset by a decrease in marketing expenses of $1.7 million.

During 2025, sales and marketing expenses as a percentage of revenue decreased to 25% from 26% due to higher revenue compared to 2024. We expect our investments in sales and marketing will increase in absolute dollars on a year-over-year basis, but decline as a percentage of revenue, as we continue to land new customers and expand our platform, cloud and managed services.

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Research and Development Expenses

Research and development expenses include personnel costs, outside contractor and consulting services, depreciation on lab equipment, costs of prototypes and overhead allocations. The following table sets forth our research and development expenses (dollars in thousands):

Percent of revenue 19 % 22 %

Percent of gross profit 33 % 40 %

The increase in research and development expenses of $10.5 million during 2025 compared with 2024 was mainly due to increases in stock-based compensation of $4.3 million, outside services of $3.7 million, depreciation and amortization of $1.9 million and prototypes and test equipment expenses of $1.7 million. These increases were partially offset by decreases in facility expenses of $1.2 million.

During 2025, research and development expenses as a percentage of revenue decreased to 19% from 22% due to the increase in revenue, and research and development expenses as a percentage of gross profit decreased to 33% from 40% due to the increase in gross profit. We expect our investments in research and development to increase in absolute dollars and as a percentage of gross profit in the short term as we accelerate the development of AI functionality and capabilities of our platform, cloud and managed services.

General and Administrative Expenses

General and administrative expenses consist primarily of personnel costs related to our executive, finance, human resources, information technology and legal organizations, outside consulting services, insurance, facilities and fees for professional services. Professional services consist of outside audit, legal, accounting and tax services. The following table sets forth our general and administrative expenses (dollars in thousands):

Percent of revenue 11 % 12 %

The increase in general and administrative expenses of $9.5 million in 2025 compared to 2024 was mainly due to increases in personnel expenses of $6.1 million and stock-based compensation of $2.9 million.

During 2025, general and administrative expenses as a percentage of revenue decreased to 11% from 12% due to higher revenue compared to 2024. We expect our general and administrative investments to increase in absolute dollars but decline as a percentage of revenue.

Interest Income and Other Expense, Net

The following table sets forth our interest income and other expense, net (dollars in thousands):

Interest income and other expense, net increased by $1.8 million in 2025 compared with 2024 mainly due to a larger average cash balance offset partially by a decrease in interest rates.

Income Tax (Benefit)

The following table sets forth our income tax (benefit) (dollars in thousands):

Effective tax rate 48 % 6 %

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During 2025, our current tax expense was $3.4 million, and our deferred tax expense was $12.9 million. Our effective tax rate was higher than the federal statutory rate of 21% primarily due to the impact of non-deductible stock-based compensation offset by the favorable impact of U.S. federal research tax credits.

During 2024, our current tax expense was $8.1 million, and our deferred tax benefit was $10.0 million. Our effective tax rate was lower than the federal statutory rate of 21% primarily due to the impact of stock-based compensation, foreign operations, valuation allowance and uncertain tax positions, offset by research and development tax credits and provision to return adjustments.

We continue to maintain a valuation allowance of $32.3 million on certain state deferred tax assets that we believe are not more likely than not to be realized in future periods.

Our income taxes may be subject to fluctuation during the year and in future years as new information is obtained, which may affect the assumptions used to estimate the annual effective tax rate, including factors such as actual results differing from our estimates of pre-tax earnings in the various jurisdictions in which we operate, which could impact the recognition of our deferred tax assets, the recognition or de-recognition of tax benefits related to uncertain tax positions and changes in or the interpretation of tax laws in jurisdictions where we conduct business.

2024 Compared to 2023

For a comparison of our results of operations for the years ended December 31, 2024 and 2023, see Item 7 “Management’s Discussion and Analysis of Financial Condition and Results of Operations” of our Annual Report on Form 10-K for the year ended December 31, 2024 filed with the SEC on February 21, 2025.

Liquidity and Capital Resources

We fund our operations and investing activities primarily through cash flow generated from operations and sales of our common stock. As of December 31, 2025, we had cash, cash equivalents and marketable securities of $388.1 million, which consisted of deposits held at banks and major financial institutions and highly liquid marketable securities such as U.S. government securities and commercial paper. This includes $12.4 million of cash primarily held by our foreign subsidiaries. As of December 31, 2025, our liability for taxes that would be payable because of repatriation of undistributed earnings of our foreign subsidiaries was limited to foreign withholding taxes as the future distribution is not expected to be taxable in the U.S.

The following table presents the cash inflows and outflows by activity during 2025 and 2024 (in thousands):

Years Ended December 31,

Net cash provided by operating activities $ 134,953 $ 68,400

Net cash used in investing activities (6,373) (109,530)

Net cash provided by (used in) financing activities (28,434) 20,897

Operating Activities

Our operating activities provided cash of $135.0 million in 2025 and $68.4 million in 2024. The increase in net cash provided by operating activities during 2025 as compared to 2024 was due primarily to an increase in our net operating results after adjustment of non-cash charges of $87.4 million partially offset by a decrease in our net cash inflow resulting from changes in operating assets and liabilities of $20.9 million. Non-cash charges consisted of stock-based compensation of $87.9 million, depreciation and amortization of $17.7 million and deferred income taxes of $12.9 million partially offset by net accretion of available-for-sale securities of $3.7 million.

In 2025, cash inflows from changes in operating assets and liabilities primarily consisted of an increase in accounts payable of $21.5 million due to increased inventory purchases, a decrease in prepaid expenses and other assets of $17.3 million due to a reduction in our inventory deposits, an increase in accrued liabilities of $11.8 million mainly due to incentive compensation related accruals and an increase in deferred revenue of $2.6 million. These changes were partially offset by increases in inventory of $31.0 million and accounts receivable of $20.0 million to support increased revenue.

Investing Activities

In 2025, net cash used in investing activities of $6.4 million consisted capital expenditures of $19.4 million, primarily consisting of purchases of test and computer equipment, partially offset by net maturities and sales of marketable securities of $13.0 million.

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Financing Activities

In 2025, net cash used in financing activities of $28.4 million consisted of purchases of our common stock of $93.6 million partially offset by the issuance of common stock related to our equity plans of $65.2 million.

2024 Compared to 2023

For a discussion of our liquidity and capital resources and our cash flow activities for the years ended December 31, 2024 and 2023, see Item 7 “Management’s Discussion and Analysis of Financial Condition and Results of Operations,” of our Annual Report on Form 10-K for the year ended December 31, 2024, filed with the SEC on February 21, 2025.

Working Capital and Capital Expenditure Needs

Our material cash commitments include non-cancelable firm purchase commitments, normal recurring trade payables, compensation-related and expense accruals and operating leases. We believe that our outsourced approach to manufacturing provides us significant flexibility in both managing inventory levels and financing our inventory. Furthermore, we have a common stock repurchase program which had $109.3 million available as of December 31, 2025. In January 2026, our Board of Directors authorized a $125.0 million increase to this program. In 2026 to date, we repurchased $148.7 million of our common stock. Our stock repurchase program does not require us to purchase a specific number of shares and may be modified, suspended or terminated at any time.

We believe, based on our current operating plan and expected operating cash flows, that our existing cash, cash equivalents and marketable securities will be sufficient to meet our anticipated cash needs for at least the next twelve months. If we are unable to generate sufficient cash flows or obtain other sources of liquidity, we will be forced to limit or terminate our stock repurchase program, limit our development activities, reduce our investment in growth initiatives and/or institute cost-cutting measures, all of which may adversely impact our business and potential growth.

Contractual Obligations and Commitments

Our principal commitments as of December 31, 2025 consisted of our contractual obligations under non-cancelable outstanding purchase obligations and operating lease obligations for office space. The following table summarizes our contractual obligations as of December 31, 2025 (in thousands):

Payments Due by Period

Total Less Than 1 Year 1-3 Years 3-5 Years More Than 5 Years

(1) Represents outstanding purchase commitments to be delivered by our third-party manufacturers and other vendors such as enterprise software vendors. See Note 5 “Commitments and Contingencies”of the Notes to Consolidated Financial Statements included in this Annual Report on Form 10-K for further discussion regarding our outstanding purchase commitments.

(2)Future minimum operating lease obligations in the table above primarily include payments for our office locations, which expire at various dates through 2033. See Note 5 “Commitments and Contingencies” of the Notes to Consolidated Financial Statements included in this Annual Report on Form 10-K for further discussion regarding our operating leases.

ITEM 7A. Quantitative and Qualitative Disclosures About Market Risk

Interest Rate Risk

The primary objectives of our investment activity are to preserve principal, provide liquidity and maximize income without significantly increasing risk. By policy, we do not enter into investments for trading or speculative purposes. As of December 31, 2025, we had cash, cash equivalents and marketable securities of $388.1 million, which was held primarily in cash, money market funds and highly liquid marketable securities such as U.S. government securities, corporate debt and commercial paper. Due to the nature of these money market funds and highly liquid marketable securities, we believe that we do not have any material exposure to changes in the fair value of our cash equivalents and marketable securities because of changes in interest rates.

Foreign Currency Exchange Risk

Our primary foreign currency exposures are described below.

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Economic Exposure

The direct effect of foreign currency fluctuations on our sales and expenses has not been material because our sales and expenses are primarily denominated in U.S. dollars, or USD. However, we are indirectly exposed to changes in foreign currency exchange rates to the extent of our use of foreign CMs whom we pay in USD. Increases in the local currency rates of these vendors in relation to USD could cause an increase in the price of products that we purchase. Additionally, if the USD strengthens relative to other currencies, such strengthening could have an indirect effect on our sales to the extent it raises the cost of our products to non-U.S. customers and thereby reduces demand. A weaker USD could have the opposite effect. The precise indirect effect of currency fluctuations is difficult to measure or predict because our sales are influenced by many factors in addition to the impact of such currency fluctuations.

Translation Exposure

Our sales contracts are primarily denominated in USD and, therefore, most of our revenue is not subject to foreign currency risk. We are directly exposed to changes in foreign exchange rates to the extent such changes affect our expenses related to our foreign assets and liabilities with our subsidiaries in China, India, the United Kingdom and Ireland, whose functional currencies are Chinese Renminbi, or RMB, Indian Rupee, or INR, British Pounds Sterling, or GBP, and Euro, or EUR.

Our operating expenses are incurred primarily in the U.S. and Canada (Canadian Dollar, or CAD), in China associated with our research and development operations that are maintained there, in India for our center of excellence and in the United Kingdom and Ireland for our international sales and marketing activities. Our operating expenses are generally denominated in the functional currencies of our subsidiaries in which the operations are located. The percentages of our operating expenses denominated in the following currencies for the indicated fiscal years were as follows:

Years Ended December 31,

EUR 1 — —

If USD had appreciated or depreciated by 10%, relative to RMB, INR, CAD, GBP and EUR our operating expenses for 2025 would have decreased or increased by approximately $9.0 million, or approximately 2%.

Foreign exchange rate fluctuations may also adversely impact our financial position as the assets and liabilities of our foreign operations are translated into USD in preparing our Consolidated Balance Sheets. The effect of foreign exchange rate fluctuations on our consolidated financial position for the year ended December 31, 2025 was a net translation loss of $0.1 million. This loss is recognized as an adjustment to stockholders’ equity through “Accumulated other comprehensive income (loss).”

Transaction Exposure

We have certain assets and liabilities, primarily accounts receivable and accounts payable (including inter-company transactions) that are denominated in currencies other than the relevant entity’s functional currency. In certain circumstances, changes in the functional currency value of these assets and liabilities create fluctuations in our reported consolidated financial position, cash flows and results of operations. Periodically, we use derivatives to hedge against fluctuations in foreign exchange rates. We do not enter into derivatives for speculative or trading purposes. We use foreign currency forward contracts to mitigate variability in gains and losses generated from the re-measurement of certain assets denominated in foreign currencies. These foreign exchange forward contracts typically have maturities of approximately one to two months. As of December 31, 2025, we had no forward contracts outstanding. Transaction gains and losses on these foreign currency denominated assets and liabilities are recognized each period within “Other expense, net” in our Consolidated Statements of Comprehensive Income (Loss). During the year ended December 31, 2025, the net loss we recognized related to these foreign currency denominated assets and liabilities was approximately $0.4 million.

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ITEM 8. Financial Statements and Supplementary Data

Report of Independent Registered Public Accounting Firm 39

Consolidated Balance Sheets, As of December 31, 2025 and 2024 41

Notes to Consolidated Financial Statements 45

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Report of Independent Registered Public Accounting Firm

To the Stockholders and Board of Directors

Calix, Inc.:

Opinions on the Consolidated Financial Statements and Internal Control Over Financial Reporting

We have audited the accompanying consolidated balance sheets of Calix, Inc. and subsidiaries (the Company) as of December 31, 2025 and 2024, the related consolidated statements of comprehensive income (loss), stockholders’ equity, and cash flows for each of the years in the three-year period ended December 31, 2025, and the related notes (collectively, 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.

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 years in the three-year period ended December 31, 2025, in conformity with U.S. generally accepted accounting principles. 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 Committee of Sponsoring Organizations of the Treadway Commission.

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 the accompanyingManagement’s Report on Internal Control Over Financial Reporting. Our responsibility is to express an opinion on the Company’s consolidated financial statements and an opinion 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 (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) 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 (3) 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 Matter

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: (1) relates to accounts or disclosures that are material to the consolidated financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of a critical audit matter 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.

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Evaluation of net realizable value of components and finished goods inventory and excess and obsolete component liabilities

As discussed in Notes 1 and 4 to the consolidated financial statements, the Company has components and finished goods inventories with a carrying value of $133.7 million and excess and obsolete component liabilities as of December 31, 2025. The Company writes down the on-hand inventory carrying value for excess or obsolete inventory and records a liability for excess and obsolete component inventory that the Company is obligated to purchase from its suppliers. These write-downs and accruals are based on assumptions about future demand for products, market conditions, potential obsolescence of technology, product life cycle, and whether pricing trends or forecasts indicate that the carrying value of inventory exceeds the estimated selling price. These factors are impacted by changes in economic conditions, technology, and customer base as well as new product introductions and require significant estimates that may include elements that are uncertain.

We identified the evaluation of net realizable value of inventory and excess and obsolete component liabilities as a critical audit matter. Evaluation of the Company’s forecasted demand, including the Company’s determination of the effect of market and economic conditions, technology changes, changes in the customer base, new product introductions, and discontinuation of products required significant auditor judgment.

The following are the primary procedures we performed to address this critical audit matter. We evaluated the design and tested the operating effectiveness of certain internal controls related to the Company’s inventory process. This included controls over the reviews of the estimates of the net realizable value of excess or obsolete components and finished goods inventory and liabilities for losses on components the Company is obligated to purchase from its suppliers. For a selection of inventory items owned by the Company, we (1) reperformed the analysis provided by the Company to assess the accuracy of the net realizable value of inventory by comparing historical sales activity, customer order backlog, or demand forecasts to the inventory on hand quantities, and (2) performed inquiries of Company’s personnel or inspected documents regarding product end of life announcements, technology changes, and new product introductions. For a selection of components subject to the Company’s purchase commitments, we (1) evaluated the reasonableness of management’s assumptions used to estimate the excess and obsolete component liabilities by considering historical sales activity, customer order backlog, or demand forecasts of the related finished products and (2) performed inquiries of Company’s personnel or inspected documents regarding product end of life announcements, technology changes, new product introductions, and historical reimbursements to suppliers for excess and obsolete components.

/s/ KPMG LLP

We have served as the Company’s auditor since 2016.

Santa Clara, California

February 20, 2026

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CALIX, INC.

CONSOLIDATED BALANCE SHEETS

(In thousands, except par value)

December 31,

ASSETS

Current assets:

Prepaid expenses and other current assets 70,345 105,596

LIABILITIES AND STOCKHOLDERS’ EQUITY

Current liabilities:

Long-term portion of deferred revenue 19,890 20,883

Commitments and contingencies (See Note 5)

Stockholders’ equity:

Accumulated other comprehensive loss (408) (612)

See accompanying notes to consolidated financial statements.

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CALIX, INC.

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)

(In thousands, except per share data)

Years Ended December 31,

Revenue:

Cost of revenue:

Operating expenses:

Interest income and other expense, net:

Net income (loss) per common share:

Other comprehensive income, net of tax:

Unrealized gain on available-for-sale marketable securities, net 343 187 1,701

Foreign currency translation adjustments, net (139) (140) 113

Total other comprehensive income, net of tax 204 47 1,814

See accompanying notes to consolidated financial statements.

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CALIX, INC.

CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY

(In thousands)

Accumulated

Additional Other Total

Common Stock Paid-in Comprehensive Accumulated Stockholders’

Shares Amount Capital Loss Deficit Equity

Other comprehensive income — — — 1,814 — 1,814

Other comprehensive income — — — 47 — 47

Other comprehensive income — — — 204 — 204

See accompanying notes to consolidated financial statements.

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CALIX, INC.

CONSOLIDATED STATEMENTS OF CASH FLOWS

(In thousands)

Years Ended December 31,

Operating activities:

Net accretion of available-for-sale securities (3,697) (5,286) (4,199)

Changes in operating assets and liabilities:

Investing activities:

Financing activities:

Payments related to financing arrangements — — (11,678)

Net cash provided by (used in) financing activities (28,434) 20,897 (65,926)

Effect of exchange rate changes on cash and cash equivalents (222) (14) 256

Net increase (decrease) in cash and cash equivalents 99,924 (20,247) (15,664)

Supplemental disclosures of cash flow information:

Interest paid $ — $ — $ 253

Non-cash investing activities:

See accompanying notes to consolidated financial statements.

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CALIX, INC.

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS

1. Description of Business and Significant Accounting Policies

Company

Calix, Inc. (together with its subsidiaries, “Calix,” “we,” “us,” or “our”) was incorporated in August 1999 and is a Delaware corporation. We develop, market and sell platform, cloud and managed services, which are powered by agentic AI, that enable communications service providers (“CSPs”) of all types and sizes to innovate and transform their businesses to focus on delivering an outstanding subscriber experience and become Communication Experience Providers (“CXPs”). The platform combines the Calix Agent WorkforceTM with intelligent appliances, software, cloud and fully integrated SmartLifeTM managed services to enable simplified business models that acquire, retain and grow subscribers and revenue. Calix Customer Success guides service providers through every stage of their transformation journey with expertise across technology, business and market insights. Our partner community extends innovation so customers can grow their businesses across markets at scale. With deep broadband expertise and an end-to-end approach from the datacenters’ access edge to every residential, business and municipal subscriber location, Calix enables any service provider to simplify operations, engagement, and service; innovate for their subscribers; and grow value for members, investors, and the communities they serve. This focus on subscriber experience allows CXPs to expand their brand through increased subscriber acquisition, loyalty and revenue while reducing their operating costs.

Basis of Presentation and Accounting Guidance

The accompanying consolidated financial statements have been prepared in accordance with the requirements of the U.S. Securities and Exchange Commission (“SEC”) and U.S. generally accepted accounting principles (“GAAP”). All significant intercompany balances and transactions have been eliminated in consolidation. Any reference in these notes to applicable accounting guidance is meant to refer to the authoritative U.S. GAAP as found in the Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”).

Use of Estimates

The preparation of financial statements is in conformity with GAAP, which requires management to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. For Calix, these estimates include, but are not limited to, allowances for doubtful accounts and sales returns, excess and obsolete inventory, allowances for obligations to our contract manufacturers, valuation of stock-based compensation, useful lives assigned to long-lived assets, standard and extended warranty costs, realizability of deferred tax assets and uncertain tax positions and contingencies. Actual results could differ from those estimates, and such differences could be material to our financial position and results of operations.

Revenue Recognition

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Observable prices of a product or service when we sell them separately based on stratification by classes of customers and products are the best estimate of stand-alone selling prices. However, when stand-alone selling prices are not directly observable, they are estimated, and judgment is required in their determination. In these instances, we determine stand-alone selling prices using all other available information, which may include pricing practices relative to geographies, market conditions, competitive landscape, characteristics of targeted customers for hardware products, internal costs and gross margin objectives for services and internal costs and value assessments for subscriptions.

Cost of Revenue

Cost of revenue consists primarily of finished goods inventory purchased from our contract manufacturers, payroll and related expenses associated with managing the relationships with contract manufacturers, depreciation of manufacturing test equipment, warranty and retrofit costs, excess and obsolete inventory costs, allowances for obligations to our contract manufacturers, shipping charges and amortization of certain intangible assets. It also includes contractor and other costs of services incurred directly related to the delivery of services to customers.

Warranty and Retrofit

We offer limited warranties for our hardware products for a period of one or five years, depending on the product type. We recognize estimated costs related to warranty activities as a component of cost of revenue upon product shipment or upon identification of a specific product failure. Under certain circumstances, we also provide fixes on specifically identified performance failures for products that are outside of the standard warranty period and recognize estimated costs related to retrofit activities as a component of cost of revenue upon identification of such product failures. We recognize estimated warranty and retrofit costs when it is probable that a liability has been incurred and the amount of loss is reasonably estimable. The estimates are based upon historical and projected product failure and claim rates, historical costs incurred in correcting product failures and information available related to any specifically identified product failures. Judgment is required in estimating costs associated with warranty and retrofit activities, and our estimates are limited to information available to us at the time of such estimates. In some cases, such as when a specific product failure is first identified or a new product is introduced, we may initially have limited information and limited historical failure and claim rates upon which to base our estimates, and such estimates may require revision in future periods. The recorded amount is adjusted from time to time for specifically identified warranty and retrofit exposure. Actual warranty and retrofit expenses are charged against our estimated warranty and retrofit liability when incurred. Factors that affect our warranty and retrofit liability include the number of active installed units and historical and anticipated rates of warranty and retrofit claims and cost per claim.

Stock-Based Compensation

Stock-based compensation expense associated with stock options, restricted stock awards (“RSAs”) and purchase rights under the Amended and Restated Employee Stock Purchase Plan (the “ESPP”) and the non-executive Stock Purchase and Matching Plan (“SPMP”) is measured at the grant date based on the fair value of the award and is recognized, net of forfeitures, as expense over the remaining requisite service period (generally the vesting period) on a straight-line basis.

The fair value of stock option and employee stock purchase right under the ESPP is estimated at the grant date using the Black-Scholes option valuation model. The fair value of the employee stock purchase right under the SPMP and RSAs is based on closing market price of our common stock on the date of grant.

Stock-based compensation expense associated with performance stock options (“PSOs”) with graded vesting features and which contain both a performance and a service condition is measured based on fair value of stock options estimated at the grant date using the Black-Scholes option valuation model, and is recognized, net of forfeitures, as expense over the requisite service period using the graded vesting attribution method.

Compensation expense is only recognized if we have determined that it is probable that the performance condition will be met. We reassess the probability of vesting at each reporting period and adjusts compensation expense based on our probability assessment.

Loss Contingencies

We occasionally face legal proceedings from business activities. We evaluate the likelihood of an unfavorable outcome and record a loss contingency when the loss is probable and reasonably estimable. This assessment involves significant judgment and uncertainty, influenced by factors beyond our control. We estimate potential losses based on available information and reassesses these estimates quarterly. Changes in estimates could impact our business, operating results or financial condition. Actual outcomes may differ from these estimates, potentially affecting us materially.

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Credit Risk and Inventory Supplier Concentrations

Financial instruments that potentially subject us to significant concentrations of credit risk consist primarily of cash, cash equivalents, marketable securities and accounts receivable. Cash equivalents consist of money market funds and marketable securities with a maturity at the date of purchase of ninety days or less, which are invested through financial institutions in the United States. Deposits in and investments held by these financial institutions may, at times, exceed federally insured limits. We have not experienced any losses in such accounts. We also have approximately $12.4 million of cash held by our foreign subsidiaries in India, China and the United Kingdom. We believe that the financial institutions that hold our cash and cash equivalents are financially sound and, accordingly, minimal credit risk exists with respect to these cash and cash equivalents.

We depend primarily on a small number of outside contract manufacturers (“CMs”) and original design manufacturers (“ODMs”) for the bulk of our finished goods inventory. We generally purchase our products through purchase orders with our suppliers. While we seek to maintain a sufficient supply of our products, our business and results of operations could be adversely affected by a stoppage or delay in receiving such products, the receipt of defective parts, an increase in price of such products or our inability to obtain lower prices from our CMs, ODMs and other suppliers in response to competitive pressures.

Fair Value of Financial Instruments

The carrying amounts of cash and cash equivalents, trade receivables, accounts payable and other accrued liabilities approximate their fair value due to their relatively short-term nature. Marketable securities are valued using quoted market prices in active markets to determine fair value.

Cash, Cash Equivalents and Marketable Securities

Cash equivalents and marketable securities are stated at amounts that approximate fair value based on quoted market prices.

We have invested our excess cash primarily in money market funds and highly liquid marketable securities such as U.S. treasury securities, corporate debt instruments, commercial paper and U.S. government securities. We consider all investments with maturities of three months or less when purchased to be cash equivalents. Marketable securities represent highly liquid U.S. treasury securities, corporate debt instruments, commercial paper and U.S. government securities with maturities greater than 90 days at date of purchase. Marketable securities with maturities greater than one year are classified as current because management considers all marketable securities to be available for current operations.

Our investments have been classified and accounted for as available-for-sale. Such investments are recorded at fair value and unrealized holding gains and losses are reported as a separate component of comprehensive loss in the stockholders’ equity until realized. Realized gains and losses on sales of marketable securities, if any, are determined on the specific identification method and are reclassified from accumulated other comprehensive loss to results of operations as “Other expense, net.” Realized gains and losses were not significant for the years ended December 31, 2025 and 2024, respectively.

For our available-for-sale debt securities in an unrealized loss position, we determine whether a credit loss exists. In this assessment, among other factors, we consider the extent to which the fair value is less than the amortized cost, any changes to the rating of the security by a rating agency and adverse conditions specifically related to the security. If factors indicate a credit loss exists, an allowance for credit loss will be recorded to “Other expense, net,” limited by the amount that the fair value is less than the amortized cost basis. The amount of fair value change relating to all other factors will be recognized in other comprehensive loss.

See Note 2 “Cash, Cash Equivalents and Marketable Securities.”

Allowance for Doubtful Accounts

We maintain an allowance for doubtful accounts for expected credit losses at contract inception resulting from the inability of our customers to make required payments. We record a specific allowance and revise the expected loss based on an analysis of individual past-due balances. Additionally, based on historical write-offs and our collection experience, we record an additional allowance based on a percentage of outstanding receivables. We perform credit evaluations of our customers’ financial condition. These evaluations require judgment and are based on a variety of factors including, but not limited to, current economic trends, payment history and a financial review of the customer. Actual collection losses may differ from our estimates, and such differences could be material to our financial position and results of operations.

Inventory Valuation and Supplier Purchase Commitments

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We regularly monitor inventory on-hand and record write-downs for excess and obsolete inventory. We also evaluate our supplier purchase commitments and record a liability for excess and obsolete components consistent with the valuation of our excess and obsolete inventory and future production requirements. These write-downs and accruals are based on our assumptions of demand for our products and require significant judgment of relevant factors including a comparison of the quantity and cost of inventory on hand to our estimated forecast of customer demand, current levels of orders and backlog, market conditions, potential obsolescence of technology, product life cycles and whether pricing trends or forecasts indicate that the carrying value of inventory exceeds our estimated selling price. Factors that could influence our assumptions and judgments include changes in economic conditions, competitive dynamics, winning or losing a key customer, changes in our customers’ capital expenditures, government investment programs, technology changes, new product introductions and supply-chain lead times. Actual demand may differ from forecasted demand and may have a material effect on gross profit. If inventory is written down, a new cost basis is established that cannot be increased in future periods.

Contract Costs

We capitalize certain sales commissions related primarily to multi-year cloud-based software subscriptions and extended warranty support contracts.

Capitalized commissions are amortized as sales and marketing expenses over the period that the related revenue is recognized, which can be up to five years for extended warranty. We classify the unamortized portion of deferred commissions as current or noncurrent based on the timing of when we expects to recognize the expense. The current and noncurrent portions of deferred commissions are included in “Prepaid expenses and other current assets” and “Other assets,” respectively, in our Consolidated Balance Sheets.

Property and Equipment

Property and equipment are stated at cost, less accumulated depreciation, and are depreciated using the straight-line method over the estimated useful life of each asset. Generally, computer equipment is depreciated over two years; purchased software is depreciated over three to five years; test equipment is depreciated over three years; furniture and fixtures are depreciated over seven years; and leasehold improvements are depreciated over the shorter of the respective lease term or the estimated useful life of the asset. Maintenance and repairs are charged to expense as incurred.

Goodwill

Goodwill was recorded as a result of our acquisitions of Optical Solutions, Inc. in 2006 and Occam Networks, Inc. in 2011. We record goodwill when consideration paid in a business acquisition exceeds the fair value of the net tangible assets and the identified intangible assets acquired. Goodwill is not amortized but instead is subject to an annual impairment test or more frequently if events or changes in circumstances indicate that it may be impaired. We evaluate goodwill on an annual basis as of the end of the second quarter of each fiscal year. We have determined that it operates as a single reporting unit and, therefore, evaluates goodwill impairment at the enterprise level.

At the end of the second quarter of 2025, we completed our annual goodwill impairment test. Based on our assessment of certain qualitative factors such as market capitalization, we concluded that the fair value of Calix was more likely than not greater than the carrying amount as of July 2, 2025. As such, it was not necessary to perform the two-step quantitative goodwill impairment test at the time.

There have been no significant events or changes in circumstances subsequent to the 2025 annual impairment test that would more likely than not indicate that the carrying value of goodwill may have been impaired as of December 31, 2025. There were no impairment losses for goodwill for the years ended December 31, 2025, 2024 or 2023.

Deferred Revenue

Deferred revenue results from transactions where we billed the customer for products or services and when cash payments are received or due prior to transferring control of the promised goods or services to the customer.

Payment terms to customers typically range from net 30 to net 90 days and vary by the size and location of customer and the products or services offered. The period between the transfer of control of the promised good or service to a customer and when payment is due is not a significant financing component.

Income Taxes

We evaluate our tax positions and estimate our current tax exposure along with assessing temporary differences that result from different book to tax treatment of items not currently deductible for tax purposes. These differences result in deferred tax assets and liabilities on our Consolidated Balance Sheets, which are estimated based upon the difference between the financial statement and tax bases of assets and liabilities using the enacted tax rates that will be in effect when these differences reverse.

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In general, deferred tax assets represent future tax benefits to be received when certain expenses previously recognized in our Consolidated Statements of Comprehensive Income (Loss) become deductible expenses under applicable income tax laws or loss or credit carryforwards are utilized. Accordingly, realization of our deferred tax assets is dependent on future taxable income against which these deductions, losses and credits can be utilized.

We must assess the likelihood that deferred tax assets will be recovered from future taxable income, and if we determine that recovery is not more likely than not, we must establish a valuation allowance. Management judgment is required in determining our provision for income taxes, deferred tax assets and liabilities and any valuation allowance recorded against our net deferred tax assets.

Newly Adopted Accounting Standards

Income taxes

In December 2023, the FASB issued Accounting Standard Update (“ASU”) No. 2023-09, Income Taxes, which prescribes standardized categories and disaggregation of information in the reconciliation of provision for income taxes, requires disclosure of disaggregated income taxes paid and modifies other income tax-related disclosure requirements. We adopted the new standard effective for our 2025 annual reporting period. See footnote “9. Income Taxes.”

Recent Accounting Pronouncements Not Yet Adopted

In November 2024, the FASB issued ASU No. 2024-03, Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures, which requires additional disclosure of certain costs and expenses within the notes to the financial statements. The updated standard is effective for our annual periods beginning in 2027 and interim periods beginning in the first quarter of 2028. Early adoption is permitted. We are currently evaluating the impact that the updated standard will have on our financial statement disclosures.

In September 2025, the FASB issued ASU No. 2025-06, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software, which clarifies and modernizes the accounting for internal-use software. ASU No. 2025-06 is effective for us in the first quarter of fiscal 2028, with early adoption permitted. The standard permits application of the guidance using a prospective, retrospective, or modified transition approach. We are currently evaluating the impact that the updated standard will have on our financial statement disclosures.

There have been no other accounting pronouncements or changes in accounting pronouncements that are significant or potentially significant to our Consolidated Financial Statements.

2. Cash, Cash Equivalents and Marketable Securities

Cash, cash equivalents and marketable securities consisted of the following (in thousands):

December 31,

Cash and cash equivalents:

U.S. government agency securities 3,463 —

U.S. government securities — 7,550

Marketable securities:

U.S. government agency securities 9,027 24,411

The carrying amounts of our money market funds approximate their fair values due to their nature, duration and short maturities. As of December 31, 2025, all marketable securities were due in three years or less.

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The amortized cost and fair value of marketable securities as of December 31, 2025 were as follows (in thousands):

Amortized Cost Gross Unrealized Gains, net Fair Value

The amortized cost and fair value of marketable securities as of December 31, 2024 were as follows (in thousands):

Amortized Cost Gross Unrealized Gains, net Fair Value

3. Fair Value Measurements

We measure our cash equivalents and marketable securities at fair value on a recurring basis. Fair value is an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. We utilize the following three-tier value hierarchy which prioritizes the inputs used in measuring fair value:

Level 1 – Observable inputs that reflect quoted prices (unadjusted) for identical assets or liabilities in active markets.

Level 2 – Observable inputs other than quoted prices included in Level 1 for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-driven valuations in which all significant inputs and significant value drivers are observable in active markets.

Level 3 – Unobservable inputs to the valuation derived from fair valuation techniques in which one or more significant inputs or significant value drivers are unobservable. The fair value hierarchy also requires us to maximize the use of observable inputs, when available, and to minimize the use of unobservable inputs when determining inputs and determining fair value.

The following tables sets forth our financial assets measured at fair value on a recurring basis based on the three-tier fair value hierarchy (in thousands):

As of December 31, 2025 Level 1 Level 2 Total

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As of December 31, 2024 Level 1 Level 2 Total

4. Balance Sheet Details

Accounts receivable, net consisted of the following (in thousands):

December 31,

Allowance for doubtful accounts (365) (311)

The table below summarizes the changes in allowance for doubtful accounts and product return liability for the periods indicated (in thousands):

Allowance for doubtful accounts $ 397 $ 43 $ (136) $ 304

Inventory consisted of the following (in thousands):

December 31,

Prepaid expenses and other current assets consisted of the following (in thousands):

December 31,

Prepaid expenses and other current assets 56,458 42,976

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Property and equipment, net consisted of the following (in thousands):

December 31,

Accumulated depreciation and amortization (60,991) (55,590)

Depreciation and amortization expenses were $17.7 million, $19.6 million and $16.6 million for the years ended December 31, 2025, 2024 and 2023, respectively.

Accrued liabilities consisted of the following (in thousands):

December 31,

Compensation and related benefits $ 44,097 $ 36,004

Component inventory held by suppliers 9,665 8,855

Professional and consulting fees 4,981 5,385

Current portion of warranty and retrofit 1,961 5,288

Changes in our accrued warranty and retrofit liability were as follows (in thousands):

Years Ended December 31,

Provision for warranty and retrofit charged to cost of revenue (38) 2,268 3,282

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5. Commitments and Contingencies

Lease Commitments

We lease office space under non-cancelable operating leases. Certain of our operating leases contain renewal options and rent acceleration clauses. Future minimum payments under the non-cancelable operating leases for leases that have commenced consisted of the following as of December 31, 2025 (in thousands):

Year Ending December 31, Future Minimum Lease Payments

Total future minimum lease payments 18,382

Less imputed interest (2,789)

As of December 31, 2025, the operating lease liability consisted of the following (in thousands):

Accrued liabilities - current portion of operating leases $ 2,837

In December 2024, we entered into a new headquarters office lease agreement for 23,000 square feet in San Jose, California. The lease commenced in August 2025 for a term of 90 months. The future minimum lease payments of $8.9 million are included in the table above. We recorded a right-of-use operating lease asset and operating lease liability of $7.0 million in the third quarter of 2025. Our previous lease in San Jose, California expired in October 2025.

The above tables also include future minimum lease payments for our office facilities in Petaluma, California; Plymouth, Minnesota; Richardson, Texas; Bangalore, India; and Nanjing, China, which expire at various dates through 2031.

The weighted average discount rate for our operating leases as of December 31, 2025 was 5.4%. The weighted average remaining lease term as of December 31, 2025 was 5.7 years.

For the years ended December 31, 2025, 2024 and 2023, total rent expense was $4.5 million, $5.1 million and $4.8 million, respectively. Cash paid within operating cash flows for operating leases was $3.9 million for the year ended December 31, 2025 and $4.5 million for each of the years ended December 31, 2024 and 2023.

Purchase Commitments

Our CMs and ODMs place orders for component inventory based upon our build forecasts and pursuant to stated component lead times to ensure adequate component supply. The components are used by the CMs and ODMs to build the products included in the build forecasts. We generally do not take ownership of the components held by CMs and ODMs. We place purchase orders with our CMs and ODMs in order to fulfill our monthly finished product inventory requirements. We incur a liability when the CMs and ODMs convert the component inventory to a finished product and takes ownership of the finished goods inventory. As of December 31, 2025 and 2024, we had approximately $317.8 million and $248.7 million, respectively, of outstanding purchase commitments to be delivered by our third-party manufacturers and other vendors such as enterprise software vendors.

Litigation

From time to time, we are involved in various legal proceedings arising from the normal course of business activities. We are not currently a party to any legal proceeding that, if determined adversely to us, in management's opinion, is currently expected to individually or in the aggregate have a material adverse effect on our business, operating results or financial condition taken as a whole.

Indemnifications

From time to time, we enter into contracts that require it to indemnify various parties against claims from third parties. These contracts primarily relate to (i) certain real estate leases, under which we may be required to indemnify property owners for

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environmental and other liabilities, and other claims arising from our use of the applicable premises, (ii) agreements with our officers, directors and certain employees, under which we may be required to indemnify such persons for liabilities arising out of their relationship with us, (iii) contracts under which we may be required to indemnify customers against third-party claims that our product infringes a patent, copyright or other intellectual property right and (iv) agreements under which the we may be required to indemnify the counterparty for certain claims that may be brought against them arising from our acts or omissions with respect to the transactions contemplated by such agreements.

Because any potential obligation associated with these types of contractual provisions are not quantified or stated, the overall maximum amount of the obligation cannot be reasonably estimated. Historically, we have not been required to make payments under these obligations, and no liabilities have been recorded for these obligations in the accompanying Consolidated Balance Sheets.

6. Stockholders’ Equity

Preferred Stock

The Board of Directors has the authority, without a further vote of the stockholders, to designate and issue up to 5.0 million shares of preferred stock in one or more series and to fix the rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting any series or the designation of such series, any or all of which may be greater than the rights of common stock. The issuance of our preferred stock could adversely affect the voting power of holders of common stock and the likelihood that such holders will receive dividend payments and payments upon liquidation. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change in control of Calix or other corporate action. Since our initial public offering, the Board of Directors has not designated any rights, preference or powers of any preferred stock, and no shares of preferred stock have been issued.

Common Stock

Holders of our common stock are entitled to receive dividends, if any, as may be declared from time to time by the Board of Directors out of legally available funds. No dividends have been declared or paid as of December 31, 2025.

Stock Repurchase Program

We maintain a common stock repurchase program. Under the repurchase program, repurchases can be made from time to time using a variety of methods, which may include open market purchases, privately negotiated transactions or otherwise, all in accordance with the rules of the SEC and other applicable legal requirements. The specific timing, price and size of the purchases depends on prevailing stock prices, general economic and market conditions, and other considerations consistent with our capital allocation strategy. The repurchase program does not obligate us to acquire a particular amount of common stock, and the repurchase program may be suspended or discontinued at any time at our discretion. During the year ended December 31, 2025, we purchased 2.5 million shares of common stock for $93.6 million at an average price per share of $37.11. As of December 31, 2025, the remaining authorized balance under this program was $109.3 million. In January 2026, our Board of Directors authorized a $125.0 million increase to this program. In 2026 to date, we repurchased $148.7 million of our common stock.

Equity Incentive Plans

2019 Equity Incentive Award Plan

Employees and consultants of Calix, our subsidiaries and affiliates and our Board of Directors members are eligible to receive awards under the 2019 Equity Incentive Award Plan (the “2019 Plan”). The 2019 Plan provides for the grant of stock options, stock appreciation rights, restricted stock, restricted stock units or other stock or cash-based awards and dividend equivalents to eligible individuals. Stock options granted under the 2019 Plan are granted at a price not less than 100% of the fair market value of the common stock on the date of grant. Stock options issued under the 2019 Plan generally vest 25% on the first anniversary of the vesting commencement date and on a quarterly basis thereafter for a period of an additional three years. The options have a maximum term of ten years. At our 2025 annual meeting of stockholders, the stockholders approved an increase in the number of shares of common stock issuable under the 2019 Plan by 4.0 million shares. As of December 31, 2025, there were 3.7 million shares available for issuance under the 2019 Plan.

In February 2024, PSO awards exercisable for up to an aggregate of 2.4 million shares of common stock were granted to certain of our executives with a grant date exercise price of $34.26 per share and divided into two plans, with the first plan accounting for 75% of the total shares granted and the second plan accounting for 25% of the total shares granted. The actual number of shares earned was contingent upon achievement of annual financial targets for bookings and non-GAAP net operating income for 2024 (collectively, the “2024 Performance Targets”) during the one-year performance period. In January 2025, the Talent and Compensation Committee (“Compensation Committee”) certified the achievement related to the 2024 Performance Targets

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and determined that 58.9% of shares underlying the PSOs were earned, subject to the on-going service condition, and 41.1% of the shares underlying the PSOs were immediately forfeited. Pursuant to the grant, 25% of the earned PSOs were vested and became exercisable on the first anniversary of the grant date, and the remaining 75% of the shares of common stock will vest and become exercisable in substantially equal quarterly installments over the subsequent three years, subject to the executive’s continued service with Calix through the respective vesting dates. Stock-based compensation expense of $6.8 million and $13.1 million was recognized for the years ended December 31, 2025 and 2024, respectively, related to these awards.

In February 2025, stock option awards exercisable for up to an aggregate of 3.1 million shares of common stock were granted to certain members of our leadership team with a grant date exercise price of $39.68 per share. The actual number of shares earned is contingent upon achievement of annual corporate financial targets for bookings and non-GAAP net operating income for 2025 (collectively, the “2025 Performance Targets”) during the one-year performance period. The stock option awards will vest, subject to certification by the Compensation Committee upon the achievement of the 2025 Performance Targets, as to 25% of the shares of common stock earned on the one year anniversary of the date of grant, and as to the remaining 75% of the shares of common stock earned, in substantially equal quarterly installments over the subsequent 36 months, subject to the executive’s continuous service with Calix through the respective vesting dates. If the combined non-GAAP net operating income target and the bookings target are achieved below 50% of target, 50% of the shares would be awarded, and the balance would be forfeited. If the combined target is achieved at the minimum threshold of 50% of target, then 75% of the shares would be awarded, with an increasing percentage of shares awarded above the minimum thresholds up to 100% of the granted shares for each target. Each target result is then weighted by 50% and the combined total determines the percent of target shares. The maximum combined award is 100%.

In May 2025, the Compensation Committee modified a departed executive’s stock options to accelerate vesting and extend the exercise period for outstanding grants. As a result, a charge of $4.9 million was recognized for the year ended December 31, 2025.

In February 2026, the Compensation Committee certified the achievement related to the 2025 Performance Targets and determined that 100% of shares underlying the stock option awards were earned, subject to the on-going service condition. Stock-based compensation expense of $21.5 million was recognized for the year ended December 31, 2025 related to these awards.

The following table summarizes the stock option activity under our equity incentive plans (in thousands, except per share data):

Weighted-

Average

Weighted- Remaining

Average Contractual Aggregate

Number of Exercise Price Life Intrinsic

Shares Per Share (in years) Value (1)

During the years ended December 31, 2025, 2024 and 2023, total intrinsic value of stock options exercised was $86.5 million, $9.0 million and $16.7 million, respectively. Cash received from employee stock option exercises in 2025, 2024 and 2023 was $35.4 million, $2.8 million and $5.2 million, respectively.

During the year ended December 31, 2025, 38,000 RSAs, with a one-year vesting period, were granted to our Board of Directors with a grant date fair value of $42.65 per share.

Employee Stock Purchase Plans

We maintain two plans under which employees can purchase our common stock - the ESPP and the non-executive SPMP. In March 2025, our Board of Directors approved amending and restating the Third Amended and Restated 2017 Nonqualified

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Employee Stock Purchase Plan as the SPMP, which better describes the nature of the plan whereby when a non-executive employee buys a share, we match it. Our Board of Directors approval included reserving 2.9 million shares of our common stock under each of the purchase component and the matching component of the SPMP, including 1.25 million shares for the matching component subject to stockholder approval, with a corresponding decrease in shares authorized in the ESPP of 2.5 million shares. At our 2025 annual meeting of stockholders, the stockholders approved an increase to the authorized shares to the SPMP of 1.25 million shares of common stock under the matching component, resulting in a corresponding decrease in the shares authorized for issuance under the ESPP of 2.5 million shares. Shares were issued from the SPMP starting with the August 8, 2025 purchase period.

The ESPP allows eligible employees to purchase shares of our common stock through payroll deductions of up to 15% of their eligible compensation subject to certain Internal Revenue Code limitations. In addition, participants may purchase up to 2,000 shares of common stock in each offering period.

The offering periods under the ESPP are twosix-month offering periods from August 15th through February 14th and February 15th through August 14th of each year. The price of common stock purchased under the ESPP is 85% of the lower of the fair market value of the common stock on the commencement date and the end date of each six-month offering period. The total shares authorized for issuance under the ESPP is 9.9 million shares. As of December 31, 2025, there were 1.5 million shares available for issuance under the ESPP. During the year ended December 31, 2025, 0.3 million shares were purchased under the ESPP. As of December 31, 2025, unrecognized stock-based compensation expense of $0.4 million related to the ESPP is expected to be recognized over a remaining service period of 0.1 years.

The SPMP allows eligible employees to purchase shares of our common stock through payroll deductions of up to 25% of their eligible recurring compensation. Eligible employees have the right to (a) purchase the maximum number of whole shares of common stock that can be purchased with the elected payroll deductions during each offering period for which the employee is enrolled at a purchase price equal to the closing price of our common stock on the last day of such offering period and (b) receive an equal number of shares of our common stock that are subject to a risk of forfeiture in the event the employee terminates employment within the one year period immediately following the purchase date. The SPMP provides quarterly offering periods from February 8th through May 7th, May 8th through August 7th, August 8th through November 7th and November 8th through February 7th of each year, with a maximum of 0.35 million shares allocated per purchase period.

The maximum number of shares of common stock currently authorized for issuance under the SPMP is 5.8 million shares. As of December 31, 2025, there were 2.8 million shares available for issuance for each of the SPMP purchase and matching components. During the year ended December 31, 2025, 0.9 million shares were purchased and issued. As of December 31, 2025, unrecognized stock-based compensation expense of $12.2 million related to the SPMP is expected to be recognized over a remaining weighted-average service period of 0.8 years.

Stock-Based Compensation

The following table summarizes stock-based compensation expense (in thousands):

Years Ended December 31,

The following table summarizes the weighted-average grant date fair values of our stock-based awards granted in the periods indicated:

Years Ended December 31,

We value employee stock purchase rights under the SPMP at the closing market price of our common stock on the date of grant.

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We estimate the fair value of stock options and employee stock purchase right under the ESPP at the grant date using the Black-Scholes option-pricing model. This model requires the use of the following assumptions:

(i)Expected volatility of our common stock – We compute our expected volatility assumption based on a blended volatility (50% historical volatility and 50% implied volatility from traded options on our common stock). The selection of a blended volatility assumption was based upon our assessment that a blended volatility is more representative of our future stock price trend as it weighs the historical volatility with the future implied volatility.

(ii)Expected life of the option award – Represents the weighted-average period that the stock options are expected to remain outstanding. Our computation of expected life utilizes the simplified method in accordance with Staff Accounting Bulletin No. 110 due to the lack of sufficient historical exercise data to provide a reasonable basis upon which to estimate expected term. The mid-point between the vesting date and the expiration date is used as the expected term under this method.

(iii)Expected dividend yield – The assumption is zero based on our history of not paying dividends and no future expectations of dividend payouts.

(iv)Risk-free interest rate – Based on the U.S. Treasury yield curve in effect at the time of grant with maturities approximating the grant’s expected life.

The following table summarizes the weighted-average assumptions used in estimating the grant-date fair value of stock options and of each employee’s purchase right under the ESPP in the periods indicated:

Years Ended December 31,

Expected volatility 49 % 51 % 52 %

Expected life (years) 6.1 6.0 6.1

Years Ended December 31,

Expected volatility 41 % 48 % 47 %

Expected life (years) 0.5 0.5 0.5

In addition, we apply an estimated forfeiture rate to awards granted and record stock-based compensation expense only for those awards that are expected to vest. Forfeiture rates are estimated at the time of grant based on our historical experience. Further, to the extent our actual forfeiture rate is different from our estimate, stock-based compensation is adjusted accordingly.

As of December 31, 2025, unrecognized stock-based compensation expense by award type, net of estimated forfeitures, and their expected weighted-average recognition periods are summarized in the following table (in thousands).

Stock Option RSAs ESPPs

Unrecognized stock-based compensation expense $ 86,413 $ 561 $ 12,582

Weighted-average amortization period (in years) 2.1 0.4 0.8

We expect to recognize stock-based compensation expense of $55.5 million in 2026, $24.2 million in 2027, $15.8 million in 2028 and $4.1 million in 2029.

Shares Reserved for Future Issuance

As of December 31, 2025, we had common shares reserved for future issuance as follows (in thousands):

Stock options outstanding 13,210

Shares available for future grant under 2019 Plan 3,685

Shares available for future issuance under SPMP 5,574

Shares available for future issuance under ESPP 1,459

7. Employee Benefit Plan

We sponsor a 401(k) tax-deferred savings plan for all employees who meet certain eligibility requirements. Participants may contribute, on a pre-tax basis, a percentage of their annual compensation, but not to exceed a maximum contribution amount

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pursuant to Section 401(k) of the Internal Revenue Code. At the discretion of the Board of Directors, we may make additional matching contributions on behalf of the participants. We made matching contributions totaling $5.7 million, $5.5 million and $5.2 million in 2025, 2024 and 2023, respectively.

8. Accumulated Other Comprehensive Loss

The table below summarizes the changes in accumulated other comprehensive loss by component:

Other comprehensive income (loss) 187 (140) 47

Other comprehensive income (loss) 343 (139) 204

Assets and liabilities of our wholly owned foreign subsidiaries are translated from their respective functional currencies at exchange rates in effect at the balance sheet date, and revenue and expenses are translated at the monthly average exchanges rates. These translations result in differences called foreign currency translation adjustments. Realized foreign currency transaction gains or losses were not significant during the years ended December 31, 2025, 2024 or 2023 and were recorded in “Other expense, net” in our Consolidated Statements of Comprehensive Income (Loss). Realized gains and losses on sales of available-for-sale marketable securities, if any, are reclassified from accumulated other comprehensive loss to “Other expense, net” in our Consolidated Statements of Comprehensive Income (Loss).

9. Income Taxes

The domestic and foreign components of income before incomes taxes were as follows (in thousands):

Years Ended December 31,

Income taxes consisted of the following (in thousands):

Years Ended December 31,

Current:

Deferred:

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The effective income tax rate for the year ended December 31, 2025 differs from the statutory federal income tax rate as follows (dollars in thousands):

Provision for income taxes at U.S. federal statutory rate $ 7,175 21.0 %

U.S. federal tax:

Non-taxable or non-deductible items:

Executive compensation 666 1.9

Effects of cross-border tax laws 130 0.4

Tax credits:

Research and development tax credit (3,182) (9.3)

Foreign tax credit 384 1.1

Changes in unrecognized tax benefits 238 0.7

State and local income tax, net of federal benefit (1) 1,091 3.2

Foreign tax effects:

China:

Non-deductible share-based compensation 480 1.4

India:

Withholding tax on repatriation 457 1.3

Other foreign jurisdictions 51 0.2

(1) During the year ended December 31, 2025, state taxes in Florida, Pennsylvania, South Carolina and Texas comprised greater than 50% of the tax effect in this category.

As previously disclosed, prior to the adoption of ASU 2023-09, the effective income tax rate differs from the statutory federal income tax rate as follows:

Years Ended December 31,

Federal statutory rate 21.0 % 21.0 %

Impact of state taxes 0.9 2.6

Foreign operations (4.2) 0.8

U.S. tax impact of foreign operations (0.4) (2.4)

Stock-based compensation (24.3) 8.8

Other permanent items (1.7) 2.5

Provision to return adjustments 6.4 (9.7)

Valuation allowance (2.1) —

Attribute expiration (0.1) 0.8

Uncertain tax positions (3.5) 4.7

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The significant components of our deferred tax assets were as follows (in thousands):

December 31,

Deferred tax assets:

Net operating loss carryforwards $ 22,836 $ 1,405

Deferred tax liabilities:

Undistributed earnings of foreign subsidiaries (1,056) —

Total deferred tax liabilities (7,342) (2,766)

All deferred taxes, along with any related valuation allowance, are classified in the Consolidated Balance Sheet as long-term.

A valuation allowance is required when, based upon an assessment of various factors, including recent operating loss history, anticipated future earnings, and prudent and reasonable tax planning strategies, it is more likely than not that some portion of the deferred tax assets will not be realized. At each reporting period, we assess the estimated future realizability of the gross carrying value of our deferred tax assets. Our periodic assessments take into consideration both positive evidence (future profitability projections for example and recent financial performance) and negative evidence (historical financial performance for example) as it relates to evaluating the future recoverability of our deferred tax assets. The valuation allowance increased by $1.8 million from 2024 to 2025. We continue to maintain a valuation allowance of $32.3 million on certain California state deferred tax assets that we believe are not more likely than not to be realized in future periods.

As of December 31, 2025, we had a U.S. federal net operating loss of approximately $96.8 million that does not expire and $41.1 million of state net operating losses which will expire at various dates through 2040 if not utilized. Additionally, we have U.S. federal, California and other state research and development credits of approximately $45.5 million, $55.3 million and $2.6 million as of December 31, 2025, respectively. The U.S. federal research and development credits will expire at various dates through 2045 if not utilized. The California research and development credits have no expiration date. The credits related to other various U.S. states have begun to expire and will continue to expire at various dates through 2040.

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Income Taxes Paid

Income taxes paid (net of refunds) were as follows (in thousands):

States:

Pennsylvania 450

South Carolina 359

Foreign:

Cash taxes paid prior to the adoption of ASU 2023-09 were $5.9 million in 2024 and $11.9 million in 2023.

Uncertain Tax Positions

ASC 740, “Income Taxes,” prescribes a recognition threshold and measurement attribute to the financial statement recognition and measurement of a tax position taken or expected to be taken in a tax return. The guidance also provides guidance on derecognition, classification, accounting in interim periods and disclosure requirements for uncertain tax positions. The standard requires us to recognize the financial statement effects of an uncertain tax position when it is more likely than not that such position will be sustained upon audit. We recognize accrued interest and penalties related to unrecognized tax benefits as interest expense and income tax expense, respectively, in our Consolidated Statements of Comprehensive Income (Loss).

Our unrecognized tax benefits were as follows (in thousands):

Years Ended December 31,

Reduction for tax positions related to prior year (4) (121) (19)

Additions for tax positions related to prior year 275 — 580

Additions for tax positions related to current year 2,389 2,310 2,673

As of December 31, 2025 and 2024, we had unrecognized tax benefits of $37.3 million and $34.6 million, respectively, $20.6 million of which would affect our effective tax rate if recognized. Accrued interest or penalties for uncertain tax positions as of December 31, 2025 was not significant.

We file tax returns in the United States and various state jurisdictions, China, India, Ireland and the United Kingdom. The tax years 2000 through 2025 remain open and subject to examination by the appropriate governmental agencies due to tax attribute carryforwards. We are currently under examination in India, and no adjustments have been proposed to date.

In December 2021, the Organization for Economic Cooperation and Development enacted model rules for a new global minimum tax framework (“Pillar Two”), and certain governments in countries which we operate have enacted local Pillar Two legislation, with an effective date from January 1, 2024. We currently do not expect Pillar Two to have a material impact on our financial statements.

In July 2025, President Trump signed the One Big Beautiful Bill Act ("OBBBA"), which includes a broad range of tax reform provisions affecting businesses. The OBBBA includes numerous changes to existing tax law including extending or making permanent certain business and international tax measures initially established under the 2017 Tax Cuts and Jobs Act, which were set to expire. Additionally, the OBBBA permanently eliminates the requirement to capitalize and amortize U.S.-based research and experimental expenditures over five years, making these expenditures fully deductible in the period incurred. The Company has accounted for the effects of the OBBBA in the financial statements for the period ended December 31, 2025, of which the primary impact is a reduction of current tax liabilities and a corresponding reduction in deferred tax assets. The

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Company will continue to evaluate the impacts of OBBBA including the potential impacts on future periods and tax planning strategies.

10. Net Income (Loss) Per Common Share

The computation of basic and diluted net income (loss) per common share for the periods indicated was as follows (in thousands, except per share data):

Years Ended December 31,

Numerator:

Denominator:

Effect of dilutive potential common shares 3,264 — 3,340

Basic net income (loss) per common share $ 0.27 $ (0.45) $ 0.44

Diluted net income (loss) per common share $ 0.26 $ (0.45) $ 0.42

Potentially dilutive shares excluded, weighted-average 7,059 12,057 4,688

Unvested restricted stock awards are included in the calculation of basic weighted-average shares for all periods presented with net income because such shares are participating securities; however, the impact was immaterial.

Potentially dilutive shares have been excluded from the computation of diluted net income per common share when their effect is antidilutive. These antidilutive shares were primarily from stock options.

11. Revenue from Contracts with Customers

Contract Asset

Contract assets include amounts recognized as revenue prior to our contractual right to bill the customer and are included in “Prepaid expenses and other current assets” in our Consolidated Balance Sheets. Amounts are billed in accordance with the agreed-upon contractual terms. The balance as of December 31, 2025 was $4.8 million of which we expect to bill 20% of the balance during 2026. The balance as of December 31, 2024 was $2.8 million.

Contract Liability

Deferred revenue was $50.3 million and $47.6 million as of December 31, 2025 and 2024, respectively. The increase in deferred revenue of $2.7 million is primarily driven by cash payments received or due in advance of satisfying our performance obligations partially offset by revenue recognized of $20.1 million that was included in the deferred revenue balance at the beginning of the year.

Revenue allocated to remaining performance obligations (“RPOs”) represents contract revenue that has not yet been recognized, which includes deferred revenue and amounts that will be invoiced and recognized as revenue in future periods but excludes variable consideration where the monthly invoicing is based on usage or where actual usage exceeds the minimum commitment. RPOs were $385.0 million as of December 31, 2025, and we expect to recognize as revenue 39% of this amount over the next 12 months and a large majority of the remainder over the two years thereafter.

Contract Costs

We capitalize certain sales commissions related primarily to multi-year subscriptions and extended warranty support for which the expected amortization period is greater than one year. As of December 31, 2025 and 2024, the unamortized balance of deferred commissions was $20.7 million and $17.9 million, respectively. For the years ended December 31, 2025, 2024 and 2023, the amount of amortization was $11.2 million, $8.9 million and $6.5 million, respectively. There was no impairment loss in relation to the costs capitalized for these respective periods.

Concentration of Customer Risk

No customer accounted for more than 10% of our revenue for the years ended December 31, 2025, 2024 and 2023.

One customer represented 12% of our accounts receivable as of December 31, 2025. Another customer represented 23% of our accounts receivable as of December 31, 2024.

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12. Segment Information

We develop, market and sell an appliance-based broadband platform, cloud and managed services, and there are no segment managers who are held accountable for operations, operating results and plans for levels or components below the unit level. Accordingly, Calix is considered to be in a single reporting segment and operating unit structure. Our chief operating decision maker (“CODM”) is our Chief Executive Officer, who reviews financial information presented on a company-wide basis, for purposes of allocating resources and evaluating financial performance. The CODM assesses the performance of the single segment and allocates resources based on revenue and measures derived from gross margin and operating income (loss) that is reported in the Consolidated Statements of Comprehensive Income (Loss). In addition, the CODM uses a measure derived from operating expenses in the Consolidated Statements of Comprehensive Income (Loss) to monitor budget versus actual results to determine Calix’s and management’s performance. We do not have intra-entity sales or transfers. The measure of the single segment assets is the consolidated assets in the Consolidated Balance Sheet. The accounting policies of the single segment are the same as described in the significant accounting policies.

Geographic Information:

A summary of revenue disaggregated by geographic region based upon the location of the customers was as follows (in thousands):

Years Ended December 31,

Our property and equipment, net of accumulated depreciation, were located in the following geographical areas (in thousands):

December 31,

Selected Financial Information:

The following table presents selected financial information with respect to our single operating segment (in thousands):

Years Ended December 31,

(1) GAAP cost of revenue adjusted for stock-based compensation and intangible asset amortization.

(2) GAAP sales and marketing operating expenses adjusted for stock-based compensation.

(3)GAAP research and development operating expenses adjusted for stock-based compensation.

(4)GAAP general and administrative operating expenses adjusted for stock-based compensation and litigation settlement (2023 only).

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(5)Other segment items consisted of stock-based compensation expense, intangible asset amortization and litigation settlement (2023 only).

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ITEM 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

There were no changes in nor any disagreements with accountants on accounting principles or practices, financial statement disclosure, auditing scope or procedures, or other reportable events requiring disclosure pursuant to Item 304(b) of Regulation S-K.

ITEM 9A. Controls and Procedures

Evaluation of Disclosure Controls and Procedures

As of the end of the period covered by this report, which we refer to as the evaluation date, we carried out an evaluation under the supervision and with the participation of management, including our principle executive officer and principle financial officer, of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act).

The purpose of this evaluation was to determine whether as of the evaluation date our disclosure controls and procedures were effective to provide reasonable assurance that the information we are required to disclose in our filings with the SEC, (i) is recorded, processed, summarized and reported within the time periods specified in the SEC’s rules and forms and (ii) accumulated and communicated to our management, including our principal executive officer and our principal financial officer, as appropriate to allow timely decisions regarding required disclosure. Based upon this evaluation, our principal executive officer and our principal financial officer concluded that our disclosure controls and procedures were effective at the reasonable assurance level as of the end of the period covered by this report.

Management’s Report on Internal Control Over Financial Reporting

Management is responsible for establishing and maintaining adequate internal control over financial reporting. Our internal control over financial reporting is 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. 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. Management has evaluated the effectiveness of our internal control over financial reporting as of December 31, 2025 using the criteria set forth in the Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission, or COSO, (2013 framework). Based on our evaluation, management has concluded that we maintained effective control over financial reporting as of December 31, 2025 based on the COSO criteria. The effectiveness of our internal control over financial reporting as of December 31, 2025 has been audited by KPMG LLP, an independent registered public accounting firm, as stated in their report included in this Annual Report on Form 10-K.

Limitations on the Effectiveness of Controls

Our disclosure controls and procedures provide our principal executive officer and our principal financial officer reasonable assurances that our disclosure controls and procedures will achieve their objectives. However, our management, including our principal executive officer and our principal financial officer, does not expect that our disclosure controls and procedures or our internal control over financial reporting can or will prevent all human error. A control system, no matter how well designed and implemented, can provide only reasonable, not absolute, assurance that the objectives of the control system are met. Furthermore, the design of a control system must reflect the fact that there are internal resource constraints, and the benefit of controls must be weighed relative to their corresponding costs. Because of the limitations in all control systems, no evaluation of controls can provide complete assurance that all control issues and instances of error, if any, within our company are detected. These inherent limitations include the realities that judgments in decision-making can be faulty, and that breakdowns can occur due to human error or mistake. Additionally, controls, no matter how well designed, could be circumvented by the individual acts of specific persons within the organization. The design of any system of controls is also based in part upon certain assumptions about the likelihood of future events, and there can be no assurance that any design will succeed in achieving its stated objectives under all potential future conditions.

Changes in Internal Control over Financial Reporting

There was no change in our internal control over financial reporting identified in connection with the evaluation required by Rule 13a-15(d) and 15d-15(d) of the Exchange Act that occurred during the fourth quarter of 2025 that has materially affected, or is reasonably likely to materially affect, our internal control over financial reporting.

ITEM 9B. Other Information

Insider Trading Agreements

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During the three months ended December 31, 2025, none of our directors or officers (as defined in Rule 16a-1(f) under the Securities Exchange Act of 1934, as amended) adopted, terminated or modified a “Rule 10b5-1 trading arrangement” or “non-Rule 10b5-1 trading arrangement,” as each term is defined in Item 408(a) of Regulation S-K, except as follows:

On November 25, 2025, John Durocher, Chief Operating Officer of the Company, adopted a Rule 10b5-1 trading arrangement (the “Durocher 10b5-1 Plan”) that is intended to satisfy the affirmative defense of Rule 10b5-1(c) of the Securities Exchange Act of 1934, as amended. The Durocher 10b5-1 Plan allows for the contemporaneous exercise of options and sale of up to 216,370 shares of Common Stock, at specific market prices, commencing on or about February 25, 2026, and continuing until all such options are exercised and the underlying shares are sold, or November 25, 2026, whichever comes first.

On November 26, 2025, Kevin Peters, Lead Independent Director of the Board of Directors of the Company, adopted a Rule 10b5-1 trading arrangement (the “Peters 10b5-1 Plan”) that is intended to satisfy the affirmative defense of Rule 10b5-1(c) of the Securities Exchange Act of 1934, as amended. The Peters 10b5-1 Plan allows for the contemporaneous exercise of options and sale of up to 39,478 shares of Common Stock, at specific market prices, commencing on or about February 25, 2026, and continuing until all such options are exercised and the underlying shares are sold, or November 25, 2027, whichever comes first.

ITEM 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

Not applicable.

PART III

ITEM 10. Directors, Executive Officers and Corporate Governance

We have an insider trading policy, or Trading Policy, governing the purchase, sale and other dispositions of our securities that applies to all of our personnel, including directors, officers, employees and other covered persons. We also follow procedures for the repurchase of our securities. We believe that our Trading Policy and repurchase procedures are reasonably designed to promote compliance with insider trading laws, rules and regulations and listing standards applicable to us. A copy of our Trading Policy is filed as Exhibit 19.1 to this Form 10-K.

Information required by this Item 10 relating to our directors is incorporated by reference to the information set forth under the captions “Proposal No. 1—Election of Directors” and “Director Compensation” and in other applicable sections of the Proxy Statement for the 2026 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission pursuant to Regulation 14A of the Exchange Act, or the Proxy Statement, to be filed within 120 days of the end of the fiscal year covered by this Report. Information required by this Item 10 relating to our officers is incorporated by reference to the information set forth under the captions “Executive Officers” and “Executive Compensation” and in other applicable sections of the Proxy Statement. Information regarding our Section 16 reporting compliance is incorporated by reference to the information set forth under the captions “Security Ownership of Certain Beneficial Owners and Management” and “Section 16(a) Beneficial Ownership Reporting Compliance” of the Proxy Statement.

We have adopted a code of ethics, which applies to all employees, officers and directors of Calix. The Code of Business Conduct and Ethics meets the requirements of a “code of ethics” as defined by Item 406 of Regulation S-K, and applies to our Chief Executive Officer, Chief Financial Officer and all other employees, as indicated above. The Code of Business Conduct and Ethics also meets the requirements of a code of conduct under NYSE listing standards. The Code of Business Conduct and Ethics is posted on our website at www.calix.com under the links “About - Investor Relations - Governance - Code of Conduct.” We intend to disclose any amendments to the Code of Business Conduct and Ethics, as well as any waivers for executive officers or directors, on our website at www.calix.com.

ITEM 11. Executive Compensation

Information required by this Item 11 relating to executive compensation and other matters is incorporated by reference to the information set forth under the caption “Compensation Discussion and Analysis” and in other applicable sections of the Proxy Statement.

ITEM 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

Information required by this Item 12 relating to security ownership of certain beneficial owners and management and related stockholder matters is incorporated by reference to the information set forth under the caption “Security Ownership of Certain Beneficial Owners and Management” and in other applicable sections of the Proxy Statement. Information regarding securities authorized for issuance under our equity compensation plans is incorporated by reference to the information set forth under the caption “Equity Compensation Plan Information” of the Proxy Statement.

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ITEM 13. Certain Relationships and Related Transactions, and Director Independence

Information required by this Item 13 relating to certain relationships and related transactions and director independence is incorporated by reference to the information set forth under the caption “Certain Relationships and Related Transactions” and in other applicable sections of the Proxy Statement.

ITEM 14. Principal Accountant Fees and Services

Our independent registered public accounting firm is KPMG LLP, Santa Clara, CA Auditor Firm ID: 185

CALX US Equity

CALX · 10-K · period ended 2025-12-31

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

ITEM 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

ITEM 9A. Controls and Procedures

ITEM 9B. Other Information

ITEM 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

ITEM 10. Directors, Executive Officers and Corporate Governance

ITEM 11. Executive Compensation

ITEM 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

ITEM 13. Certain Relationships and Related Transactions, and Director Independence

ITEM 14. Principal Accountant Fees and Services

CALX US Equity☆

CALX · 10-K · period ended 2025-12-31

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

ITEM 9. Changes in and Disagreements with Accountants on Accounting and Financial Disclosure

ITEM 9A. Controls and Procedures

ITEM 9B. Other Information

ITEM 9C. Disclosure Regarding Foreign Jurisdictions that Prevent Inspections

ITEM 10. Directors, Executive Officers and Corporate Governance

ITEM 11. Executive Compensation

ITEM 12. Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters

ITEM 13. Certain Relationships and Related Transactions, and Director Independence

ITEM 14. Principal Accountant Fees and Services

CALX US Equity