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Item 1A. Risk Factors.

Certain risk factors can significantly impact our business, liquidity, capital resources, results of operations, financial condition, and debt ratings. These risk factors might affect, alter, or change actions in executing our long-term capital strategy. Examples include, without limitation, contributing capital to any or all of our ten property and casualty insurance subsidiaries ("Insurance Subsidiaries"), issuing additional debt and/or equity securities, repurchasing our existing debt and/or equity securities, or increasing or decreasing common stockholders' dividends. We operate in a continually changing business environment, and new risk factors that we cannot predict or assess may emerge at any time. Consequently, we can neither predict such new risk factors nor assess the potential future impact on our business.

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Risks Related to our Insurance Operations

We are subject to losses from catastrophic events.

Losses from natural and human-made catastrophes can negatively impact our financial results. Examples include hurricanes, tornadoes, windstorms, earthquakes, hail, thunderstorms, severe winter weather, derechos, floods, and fires, some related to climate change, and criminal and terrorist acts, including cyber-attacks, civil unrest, and explosions. The frequency and severity of these catastrophes are inherently unpredictable, and the frequency and severity of catastrophe losses have increased globally in recent years. In many cases, the increase in catastrophe losses relate to small- to- medium-sized events that primary insurers retain and do not cede to reinsurers. We use sophisticated catastrophe modeling techniques to manage our exposure, but actual exposure and loss experience can materially differ from catastrophe model estimates. For example, catastrophe models did not fully estimate the potential for some recent catastrophe loss activity (such as Winter Storm Elliott freeze losses in December 2022) and the concurrent economic inflation on construction costs.

Our most significant natural and/or human-made catastrophe exposures are (i) hurricanes impacting the Eastern U.S., (ii) severe convective storms, including hailstorms and tornadoes, (iii) winter storms, (iv) earthquakes, and (v) terrorism events. Single storms could adversely impact our financial results, but it is also possible that we experience more than one severe catastrophic event in any given calendar year. We track our severe weather and catastrophe losses using definitions and information we obtain from Insurance Services Office, Inc.'s ("ISO") Property Claim Services unit, an internationally recognized authority on insured property losses from catastrophes in the U.S., Puerto Rico, and the U.S. Virgin Islands.

Certain factors can impact our estimates of ultimate costs for natural and/or human-made catastrophes, including:

•Inability to access portions of the affected areas after a catastrophic event;

•Scarcity of necessary labor and materials that delay repairs and increase our loss costs;

•Regulatory uncertainties, including new or expanded interpretations of coverage;

•Residual market assessment-related increases in our catastrophe losses;

•Potential fraud and inflated repair costs, partly driven by (a) demand surge post-event and (b) opportunistic service providers;

•Higher loss expenses due to shortages of claims adjusters available to appraise damage;

•Late claims reporting;

•Escalation of business interruption costs due to infrastructure disruption; and

•Whether the U.S. Secretary of the Treasury certifies an event as a terrorist act under TRIPRA.

Natural catastrophes

Temperature changes can impact weather patterns and the frequency and/or severity of catastrophes, including hurricanes, severe convective storms, wildfires, and flooding – all of which could cause our catastrophe losses to increase relative to historical levels.

A significant component of climate change risk is that the frequency and severity of extreme weather events may evolve differently relative to historical levels – leading to greater model uncertainty. Climate change models project significant differences in global regional warming above pre-industrial levels, depending on future climate mitigation levels and geographic location. These global regional differences, whether attributable to nature or human activities, include increases in (i) mean temperature in most land and ocean regions, (ii) hot extremes in most inhabited regions, (iii) heavy precipitation in several regions, and (iv) the probability of drought and precipitation deficits in some regions.

Human-made catastrophes

Cyber Attacks and Incidents

The risk of a wide-scale criminal or terrorist cyber-attack has become more significant and has drawn increased attention from IT and national security experts, U.S. policymakers, the U.S. military, and the insurance industry. There is general recognition that a wide-scale cyber-attack that simultaneously impacts multiple victims is more likely, and insurance industry systemic risk has increased. We have identified three primary sources of potential insured exposure to cyber losses: (i) cyber-specific policies designed to cover both first-party and third-party losses; (ii) affirmative cyber coverage grants included in other types of policies, such as commercial property or businessowners' policies; and (iii) "silent cyber" exposures, otherwise known as non-affirmative cyber exposures, which describes cyber risk that is neither expressly covered nor excluded in insurance policies. This exposure may exist if courts, regardless of intent, interpret policy forms without specific related coverage exclusions to provide coverage for a cyber-related incident.

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We provide cyber-specific policies to our commercial lines and personal lines customers through 100% reinsured solutions with highly-rated specialty cyber markets. These solutions allow us to meet our customers' needs for cyber insurance while mitigating our underwriting risk as we develop our expertise in the cyber insurance market.

Beyond our cyber-specific policies, some of our other insurance policies may provide coverage following a cyber event in certain circumstances:

•We offer limited first-party affirmative cyber coverage in our commercial property and businessowners' policy forms. We limited our "silent cyber" exposure through an affirmative coverage grant subject to a sub-limit.

•Our base property forms typically include a $2,000 or $10,000 cyber coverage grant. Most of our property policies also contain an affirmative endorsement providing "virus and harmful code" coverage subject to a sub-limit. Over 90% of our policies with virus/harmful code coverage on commercial property, businessowners', commercial output policy, or inland marine forms have sub-limits of $25,000 or lower. For policies effective October 1, 2022 and later, we implemented cyber incident exclusions that exclude malicious cyber except for the sub-limited coverage provided in the base ISO coverage forms and our property and businessowners' property “virus and harmful code” extension endorsements. These exclusions clarify coverage and have no premium impact.

•Most of our general liability and businessowners' policies exclude cyber-related liability losses, except for "bodily injury." Our specific cyber-exclusion and liability forms' lack of affirmative sub-limited cyber coverage, effectively limit most "silent cyber" exposure.

•By statute, workers compensation policies do not have cyber exclusions, and a cyber-attack-related workplace injury could trigger coverage.

Terrorism

We are required to participate in TRIPRA, now extended to December 31, 2027, for our Standard Commercial Lines and E&S Lines business. TRIPRA rescinded all previously approved coverage exclusions for terrorism and requires private insurers and the U.S. government to share the risk of loss on future acts of terrorism certified by the U.S. Secretary of the Treasury. Under TRIPRA, each participating insurer must pay a significant deductible of specified losses before federal assistance is available. Our $619 million deductible is based on a percentage of our prior year’s applicable Standard Commercial Lines and E&S Lines premiums. In 2025, the federal government will pay 80% of losses above the deductible, with the insurer retaining 20%. Although TRIPRA will mitigate some of our loss exposure to a large-scale terrorist attack, the size of our deductible and 20% co-participation could have a material adverse effect on our results of operations, liquidity, financial condition, financial strength, and debt ratings. If the U.S. Secretary of the Treasury does not certify specific terrorist events, we could be required to pay terrorism-related covered losses without TRIPRA's risk-sharing benefits. We also could be required to pay terrorism-related losses for customers who declined terrorism coverage.

Our primary workers compensation policies are required to cover terrorism risk, so TRIPRA applies to those policies. Insureds with non-workers compensation commercial policies can accept or decline our terrorism coverage or negotiate with us for other terms. In 2024, 84% of our Standard Commercial Lines non-workers compensation policyholders purchased terrorism coverage that included nuclear, biological, chemical, and radioactive ("NBCR") events. TRIPRA also applies to cyber liability insurance policies reported under a Terrorism Risk Insurance Program-eligible line of insurance.

Many states mandate that commercial property policies cover fire following an act of terrorism - regardless of whether the insured purchased terrorism coverage. We also sometimes elect to provide terrorism coverage for lines of business not included in TRIPRA, such as Commercial Automobile. TRIPRA has never covered personal lines of business. Our Standard Personal Lines homeowner policies exclude nuclear losses but not biological, chemical, or conventional terrorism losses. Our current reinsurance programs cover some losses from conventional foreign and domestic terrorism acts but not NBCR events.

An increase in natural or man-made catastrophe losses, including a systemic cyber-attack that produces an aggregation of property and/or casualty cyber losses, will reduce our net income and stockholders’ equity and could have a material adverse effect on our liquidity, financial strength, and debt ratings. The closer a catastrophe occurs to the end of a reporting period, the more likely we have limited information to estimate loss and loss expense reserves, increasing the uncertainty of our estimates. More comprehensive claims information available after a reporting period may result in reserve changes in subsequent periods.

Our loss and loss expense reserves may not adequately cover actual losses and expenses.

We maintain reserves for our estimated liability for loss and loss expense associated with reported and unreported insurance claims. Estimating loss and loss expense reserves is inherently uncertain, and there is no method for precisely estimating the ultimate liability for the settlement of claims. We base our loss and loss expense reserve estimates on our internal in-depth reserve review, which uses our loss experience, claims payment and reporting patterns, and our view of underlying claims frequency and severity trends. We supplement the estimates with other subjective considerations, including projected impacts

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from economic, political, social, and legal developments or trends, such as inflation, judicial trends and tort decisions, and various state legislative initiatives. We cannot predict the timing or impact of these developments or trends with certainty, and we cannot be sure the reserves we establish are adequate or will be so in the future.

We review our reserve position quarterly and adjust the reserve position accordingly. An increase in reserves (i) reduces net income and stockholders' equity, and (ii) could have a material adverse effect on our liquidity, financial strength, and debt ratings. As we underwrite new business and renew existing business, we estimate future loss cost trends in pricing our products to generate an adequate risk-adjusted return. If our future loss cost trend estimates prove to be understated, our pricing of future new and renewal business could be inadequate to cover actual loss costs, and our future loss and loss expense reserves could be understated.

Three examples of how loss and loss expense reserves might be affected by economic, political, social, or legal developments or trends are:

•If economic inflation, including medical inflation, is higher than our assumptions, our loss and loss expense reserves for our longer tail lines of business could be insufficient. For example, 2022 inflation rates reflected in the overall consumer price index ("CPI"), the Core CPI, and the Producer Price Index, were higher than in 2021. While inflation moderated in 2023 and 2024, it remains elevated relative to the Federal Reserve’s long-term 2% target. The workers compensation line of business is particularly susceptible to inflation because of its extended payment pattern and exposure to medical care services and commodities. While medical inflation has been low for several years, our workers compensation medical severity trend has risen recently. If this trend continues and medical care costs increase significantly or persist at a higher level for an extended period, our overall loss and loss expense reserves could be materially impacted. Our short-tail property lines of business are also susceptible to inflation because of their exposure to increased labor and material costs.

•Social inflation refers to the phenomenon where societal factors, such as attitudes, perceptions, and cultural changes, contribute to increased insurance claims costs and litigation. It often leads to higher payouts in legal settlements and jury awards, and impacts insurance premiums for businesses and individuals. This inflation is driven by various factors, including changing jury attitudes, increased litigation funding, larger awards in court cases, increased willingness to undergo surgery, and novel interpretations of liability. Social inflation can affect all lines of business. However, the automobile liability, general liability, and corresponding umbrella lines of business involving third-party claimants tend to be more susceptible to social inflationary impacts. Our reserve for loss and loss expense could be insufficient if impacts from social inflation exceed our assumptions.

•Various states have expanded or could expand the statute of limitations for civil actions alleging sexual abuse. By retroactively permitting previously time-barred claims, these "reviver" laws may result in insurance claims that could significantly increase loss costs and require re-evaluating previously established reserves or creating new reserves. Since reviver statutes have been enacted, we have received some notices of claims or potential claims for acts alleged to have occurred, some dating as far back as the 1950s. Without prior experience, we cannot estimate how many "reviver" claims notices we may receive. Most notices (i) are blanket notices sent by attorneys representing claimants unsure of the alleged assailant or supervising entity's insurer or policy (if any) and (ii) may not implicate any of our or a predecessor's insurance policies. For those we determine implicate one of our or a predecessor's policy, we (i) have investigated or are investigating facts, (ii) have evaluated policy terms, (iii) believe we have appropriate coverage defenses to most of these claims and/or sufficient reinsurance protections, and (iv) have considered these factors in establishing our reserves, which we believe provide a reasonable estimate of the aggregate ultimate net exposure for these claims. We face related litigation risks because policyholders and claimants may challenge our coverage positions. We discuss these risks further below in the Risk Factor entitled, "We are engaged in ordinary routine legal proceedings incidental to our insurance operations that are inherently unpredictable and could impact our reputation and/or have a material adverse effect on our consolidated results of operations or cash flows in particular quarterly or annual periods."

For further discussion on our loss and loss expense reserves, please see the "Critical Accounting Policies and Estimates" section of Item 7. "Management’s Discussion and Analysis of Financial Condition and Results of Operations." and Note 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K.

Our ability to reduce our risk exposure depends on the availability and cost of reinsurance.

We transfer a significant portion of our underwriting risk to third parties through reinsurance, which are primarily annual contracts that reimburse us for losses exceeding specified thresholds on a per-loss or an aggregate basis. Typically, our

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reinsurance coverages align with the coverages in our primary insurance policies, including coverages for catastrophes. Historically, commercial property and homeowners losses have accounted for most of our catastrophe-related reinsurance claims. We determine the amount of reinsurance we purchase by analyzing historical losses and using various modeling software programs that analyze our Insurance Subsidiaries' risks, particularly for catastrophes. Insufficient reinsurance could have a material adverse effect on our results of operations, liquidity, financial condition, financial strength, and debt ratings.

Reinsurance availability; retentions; coverage limits, terms, conditions, and exclusions; and cost depend on market conditions influenced by traditional direct- and broker-placed reinsurance, retrocessional reinsurance, and catastrophe bond market capacity. These market factors can cause fluctuations in reinsurance costs that do not necessarily correlate to our loss experience. State insurance regulators generally permit us to consider catastrophe reinsurance expense in our filed rates and rating plans. However, the conditions and timing of regulatory approval may not align with the actual reinsurance expense. Reinsurance expense increases that are not considered or approved in our filed rates and rating plans will reduce our earnings. If we cannot negotiate desired reinsurance amounts or terms, we may experience increased reinsurance expense and increased risk retention on individual or aggregate claim losses that could limit our ability to write future business.

The reinsurance market became increasingly challenging and expensive since January 1, 2023, as monetary and social inflation-driven demand for increased reinsurance coverages coincided with reduced reinsurance capacity from poor reinsurance loss experience, particularly for general liability and catastrophe and non-catastrophe property losses, increased reinsurer investment losses, and foreign exchange rate impacts. While reinsurance market conditions have since stabilized, as pricing has moderated and capacity has increased, reinsurance purchasers continue to face higher pricing and more restrictive coverage appetite from reinsurers than they did before January 1, 2023. Our Insurance Subsidiaries face increased underwriting risk and loss exposure for specific primary policy perils, like cyber and communicable diseases, which our reinsurance policies now principally exclude. Our reinsurance contracts also restrict our ability to cede certain types of potential terrorism-related losses. Increased underwriting risk from these and other risks could increase our net loss and loss expense and the volatility of our underwriting results. Decreased reinsurance availability would also increase our underwriting risk if we cannot fully place our targeted reinsurance treaty coverage on renewal.

Even with the benefits of reinsurance, our catastrophe risk exposure could have a material adverse effect on our results of operations, liquidity, financial condition, financial strength, and debt ratings.

We are exposed to credit risk.

We face credit risk in several areas of our insurance operations, including from third parties:

•Our reinsurers, which are obligated to make us payments under our reinsurance agreements. Reinsurance credit risk can fluctuate over time, increasing during periods of high industry catastrophe and liability losses. Reinsurers generally manage their significant loss exposure through their own reinsurance programs, or retrocessions, and we do not have complete details about them. If our reinsurers experience difficulty collecting on their retrocession programs or reinstating retrocession coverage after a large loss, we may not receive timely or full payment of our reinsurance claims. Consequently, we have direct and indirect counterparty credit risk to our reinsurers and the reinsurance industry, which is a global but concentrated market.

•Certain life insurance companies, if they fail to fulfill their contractual obligations to our policyholders or claimants under annuities we purchased as part of structured claims settlements.

•Some of our independent distribution partners, who collect premiums for us from policyholders.

•Some policyholders, who are directly obligated to us for premium and/or deductible payments, the timing of which may be impacted by mandated payment moratoriums.

Our exposure to credit risk could have a material adverse effect on our results of operations, liquidity, financial condition, financial strength, and debt ratings.

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We depend on distribution partners.

We market and sell our insurance products through independent, non-employee distribution partners. Independent distribution partners have – and we expect they will continue to have – a significant role in overall insurance industry premium production. While our customers find advantages in using independent distribution partners, our reliance on independent distribution partners presents risks and challenges, including:

•Competition in our distribution channel, as we must market our products and services to independent distribution partners who can access multiple carriers and markets.

•Brand recognition challenges because we closely coordinate marketing with our distribution partners and some customers do not differentiate their insurance agent from their insurer.

•Our market share growth is tied to our distribution partners' market share. Consequently, growth in our Standard Personal Lines could be more limited than in our Standard Commercial Lines. Competitors have focused on lower-cost "direct-to-customer" distribution models emphasizing digital ease and efficiencies to grow standard personal lines business market share. Continued advancements in "direct-to-customer" distribution models may impact our independent distribution partners' overall market share, make it more difficult for us to grow, or require us to establish relationships with more distribution partners.

•Aggregation and consolidation of our independent distribution partners and their market share. Some publicly traded and private equity-backed independent distribution partners have deployed consolidation strategies to acquire other independent distribution partners and increase their market share ("Aggregators") over the last decade. If more of our independent distribution partners become Aggregators or Aggregators acquire them, Aggregator demands and influence on our business could increase. For example, Aggregators could develop and implement strategies to consolidate their business with fewer insurers and demand higher base and supplemental commissions. Aggregators accounted for approximately 46% of our DPW at December 31, 2024, up from 36% three years ago. No one distribution partner is responsible for 10% or more of our combined insurance operations' premium.

Our financial condition and results of operations are impacted by our independent distribution partners' success in marketing and selling our products and services.

National and global economic conditions could adversely and materially affect our business, results of operations, financial condition, and growth.

Unfavorable economic developments, such as a decline in economic growth or increased inflation levels, could adversely affect our earnings if our policyholders need less insurance coverage, cancel existing insurance policies, modify coverage, or choose not to renew with us. Inflation could significantly impact our claims severity across multiple lines of business and could result in adverse reserve development. An economic downturn could also lead to increased credit and premium receivable risk, failure of reinsurance counterparties and other financial institutions, limits on our ability to issue new debt, reduced liquidity, and declines in our investments' fair value and financial strength ratings. These potential events and other economic factors could adversely and materially affect our business, results of operations, financial condition, and growth. During 2024, 25% of DPW in our Standard Commercial Lines business was based on payroll or sales of our underlying policyholders. An economic downturn in which our policyholders have declining revenue or employee count could adversely affect our total written premium, including audit and endorsement premium.

We write business domestically in the United States, and our insurance operations do not have direct exposure to businesses or individuals in Russia, Ukraine, and the Middle East. We do not have material exposure to investments subject to embargoes or Russian reinsurance counterparties. However, ongoing wars and conflicts continue to impact global economic, banking, commodity, and financial markets by exacerbating ongoing economic challenges, including inflation and supply chain disruption, which influence insurance loss costs, premiums, and investment valuation.

A downgrade or a potential downgrade in our financial strength or credit ratings could result in a loss of business and have a material adverse effect on our financial condition and results of operations.

A significant financial strength rating downgrade, particularly from AM Best Company ("AM Best"), would affect our ability to write new or renewal business. Most policyholders are required by various third-party agreements, primarily with lenders, to maintain insurance policies from a carrier with a minimum rating from AM Best or Standard & Poor's Global Ratings. Credit rating downgrades could also make it more expensive to access capital markets. We cannot predict rating actions issued by nationally recognized statistical rating organizations that might adversely affect our business or potential responses. Any significant downgrade in our financial strength and credit ratings below an "A-" could have a material adverse effect on our results of operations, liquidity, financial condition, financial strength, and debt ratings. For additional information on our

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current financial strength and credit ratings, refer to "Overview" in Item 1. "Business." of this Form 10-K.

Markets for insurance products and services are highly competitive and subject to rapid technological change, and we may be unable to compete effectively.

We offer our insurance products and services in a highly competitive market characterized by (i) consumer and business price sensitivity and (ii) aggressive price competition and improvements based on performance characteristics and large data sets. These factors can compact underwriting margins, new products and services, evolving industry standards, and rapid adoption of technological advancements. Our ability to compete depends heavily on our timely and consistent introduction of innovative new products and services.

We face substantial competition from a wide range of property and casualty insurance companies for customers, distribution partners, and employees. Competitors include public, private, and mutual insurance companies. Many competitors are larger and may have lower relative operating costs, lower capital costs, or greater capacity to absorb or diversify more risk while maintaining their financial strength ratings. Other competitors, such as mutual or reciprocal companies, are owned by or operated cooperatively for insureds and, unlike us, do not have shareholders who evaluate return on equity performance. Consequently, some competitors may be able to price their products more competitively.

The Internet has emerged as a significant competitive digital marketplace for existing and new competitors. Established insurance competitors are beginning to explore broader digital Internet offerings and implement artificial intelligence ("AI"). New competitors with variations on traditional business models have emerged. Because the Internet makes it easier and less expensive to bundle products and services, it is also possible that non-insurance companies conducting business on the Internet could enter the insurance business or form strategic alliances with insurers. Changes in competitors and competition, particularly on the Internet, could cause changes in the supply or demand for insurance and adversely affect our business.

The increasing importance of the Internet, technology, AI, and digital strategies in our industry also demands that we attract and retain employees in difficult-to-fill data science, advanced analytics, and information technology ("IT") roles. If we cannot attract and retain such employees, our results of operations and financial condition could be adversely affected.

We have less loss experience data than our larger competitors.

Insurers depend on access to reliable data about their policyholders and loss experience to build complex analytics and predictive models that assess risk profitability, reserve adequacy, adverse claim development potential, recovery opportunities, fraudulent activities, and customer buying habits. Because we use and depend on the aggregated industry loss data assembled by rating bureaus under the antitrust exemptions of the McCarran-Ferguson Act, we likely would be at a competitive disadvantage to larger insurers if Congress repealed the McCarran-Ferguson Act.

We expect the importance of data science and analytics to increase, becoming more complex and accurate with larger sets of relevant data. Some larger competitors have significantly more data about the performance of their underwritten risks. In comparison, we may not have sufficient volumes of loss experience data to accurately and granularly analyze and project our future costs. We supplement our data with industry loss experience from Verisk, American Association of Insurance Services, Inc., the National Council on Compensation Insurance, Inc., and other publicly available sources. While relevant, industry data may not correlate specifically to the performance of our underwritten risks or be as predictive as data on a larger book of our own business.

We are subject to various modeling risks that could have a material adverse impact on our business results.

We rely on complex financial and other statistical models, developed internally and by third parties, to predict (i) underwriting results on individual risks and our overall portfolio, (ii) claims fraud and other claims impacts, such as escalation, (iii) impacts from catastrophes, (iv) enterprise risk management capital scenarios, and (v) investment portfolio changes. We rely on these financial and other statistical models to analyze historical loss costs and pricing, claims severity and frequency trends, catastrophe losses, reinsurance attachment and exhaustion points, investment performance, portfolio risk, and our economic capital position. Flaws or limitations in financial and statistical models and their embedded assumptions could increase losses. For example, a significant component of climate change risk is that the frequency and severity of extreme weather events may evolve differently relative to historical levels – leading to greater model uncertainty. In addition, increasing insurance regulatory interest in data and model use, combined with any potential restrictions on traditional rating factors or model use, could have a material adverse impact on our financial condition and operating results. Our statistical models are extremely useful in monitoring and controlling risk, but are no substitute for senior management's experience or judgment.

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Risks Related to Our Investments Segment

Our investments are exposed to credit risk, interest rate fluctuation, and changes in value.

We depend on income from our investment portfolio for a significant portion of our revenue and earnings. Our investments can be negatively affected by (i) liquidity, (ii) credit deterioration, (iii) financial results, (iv) public equity and/or debt market changes, (v) economic conditions, including heightened levels of economic inflation, (vi) political risk, (vii) sovereign risk, (viii) interest rate fluctuations, or (ix) other factors, including civil unrest and other catastrophic events, some of which may be impacted by climate change risk.

Our investment portfolio's value is subject to credit risk from our held securities' issuers, guarantors, financial guarantee insurers, and other counterparties in certain transactions. Defaults on any of our investments by any of these parties could reduce our net investment income and increase net realized investment losses. We are subject to the risk that the issuers or guarantors of our fixed income securities may default on principal and interest payment obligations.

Additionally, we are exposed to interest rate risk, primarily related to the market price and cash flow variability associated with changes in interest rates. Consequently, the amount of our cash and cash equivalents and the value and liquidity of our marketable and non-marketable securities may fluctuate substantially. Future fluctuations in the value of our cash, cash equivalents, and marketable and non-marketable securities could result in significant losses that have a material adverse impact on our financial condition and operating results.

Our investment portfolio is exposed to climate change-related transition and physical investment risks.

•Transition risks arise from the world’s transition to a low-carbon economy, driven by government policy and regulation, advances in low-carbon technology, and shifting societal preferences and public sentiment. This transition to renewable energy sources may lead to (i) stranded assets in sectors with high carbon footprints or those closely tied to carbon-based economic activity, such as the fossil fuel and automotive industries, (ii) increased costs for infrastructure reinvestment and replacement, and litigation defense of carbon-intensive sectors, (iii) lower corporate profitability, (iv) lower property values, and (v) lower household wealth. The Paris Agreement Capital Transition Assessment defines the carbon-intensive sectors as the most exposed to transition risk: oil and gas, coal, power, automotive, cement, aviation, and steel. Carbon-intensive sectors within our fixed income securities portfolio represented about 5% and 4% of our total invested assets as of December 31, 2024 and December 31, 2023, respectively.

•Physical investment risks include the risk of investment losses on our commercial and residential mortgage-backed securities exposed to climate-related catastrophic losses that can cause business disruption, destroy capital, increase costs to recover from disasters, reduce revenue, and cause population displacement and migration. These, in turn, can lower residential and commercial property values, household wealth, and corporate profitability, potentially creating financial and credit market losses impacting insurer asset values. As of December 31, 2024, about 69% of our residential mortgage-backed securities were backed by government agencies. We generally invest in the top tranches of commercial mortgage-backed securities, which limit potential losses from property value declines. As of December 31, 2024, about 68% of our commercial mortgage-backed securities had "AAA" credit ratings.

Significant future investment value declines could require further losses recorded on securities we sell and credit losses. For more information regarding market interest rate, credit, and equity price risk, see Item 7A. "Quantitative and Qualitative Disclosures About Market Risk." of this Form 10-K.

We are subject to the risks inherent in investing in private limited partnerships.

Our alternative investments include private limited partnerships that invest in various strategies, such as private equity, private credit, and real assets. The primary assets and liabilities underlying these limited partnership investments generally do not have quoted prices in active markets for the same or similar assets. Consequently, their valuation is subject to a higher level of subjectivity and unobservable inputs than most of our other investments. We record these limited partnership investments under the equity method of accounting, so valuation decreases could negatively impact our results of operations.

Determining the amount of credit losses taken on our investments is highly subjective and could materially impact our results of operations or our financial position.

The determination of the amount of credit losses taken on our investments is based on our quarterly evaluation and assessment of our investments and known and inherent risks associated with the various asset classes. Our allowance for credit losses is subject to significant judgments and assumptions about changes in economic conditions, estimated future cash flows, and the

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accuracy of third-party information used in internal assessments. We revise our evaluations and assessments as conditions change and new information becomes available. There can be no assurance that management has accurately assessed the level of credit losses recorded in our Financial Statements. For further details on our evaluation and considerations for determining whether a security has a credit loss, please refer to "Critical Accounting Policies and Estimates" in Item 7. "Management’s Discussion and Analysis of Financial Condition and Results of Operations." of this Form 10-K.

Risks Related to Evolving Laws, Regulations, and Public Policy Debates

We are subject to complex and changing laws, regulations, and public policy debates that expose us to regulatory scrutiny, potential liabilities, increased costs, reputational harm, and other adverse effects on our business.

Our operations are subject to complex and changing state and federal laws, regulations, and public policy debates on subjects, including, without limitation, the following:

•Pricing and underwriting practices;

•Claims practices;

•Loss and loss expense reserves;

•Exiting geographic markets and/or policy cancellations or non-renewals;

•Climate change and sustainability-related issues, including reporting, investment, and other mandated actions;

•Assessments for guaranty funds, second-injury funds, and other mandatory assigned risks and reinsurance pools;

•The types, quality, and concentration of investments we make;

•Minimum capital requirements for the Insurance Subsidiaries;

•Dividends from our Insurance Subsidiaries to the Parent;

•Privacy, data security, and related public disclosures for breaches;

•Tax;

•Antitrust;

•Consumer protection;

•Advertising, media, and digital content;

•Sales;

•Billing and e-commerce;

•Intellectual property ownership and infringement;

•Technology, digital platforms, artificial intelligence, and predictive and other modeling types;

•Internet, telecommunications, and mobile communications;

•Availability of third-party software applications and services;

•Employment and workplace rules related to human resources practices and environmental, health, and safety issues;

•Anti-money laundering; and

•Corporate social responsibility.

Changes to laws and regulations can adversely affect our business by increasing our costs, limiting our ability to offer a product or service to customers, requiring changes to our business practices, or otherwise making our products and services less attractive.

While we underwrite risks only in the U.S., international regulatory developments, primarily capital adequacy and risk management requirements in the European Union ("EU"), may influence U.S. regulators as they develop or revise domestic regulatory standards.

We have designed and implemented policies and procedures to ensure compliance with applicable laws and regulations. However, we cannot provide assurance that our employees, contractors, or independent distribution partners will not violate such laws and regulations or our policies and procedures. To some degree, we have multiple regulators whose authority may overlap and may have different interpretations and/or regulations related to the same legal issues. Consequently, we have the risk that one regulator's position or interpretation may conflict with another regulator on the same point. For example, if Congress passed legislation regulating insurer solvency oversight and state regulators remained responsible for rate approval, we could be subject to a conflicting regulatory framework that could impact our profitability and capital adequacy. The cost of complying with various laws and regulations, potentially conflicting laws and regulations, and changes in those laws and regulations, could have a material adverse effect on our results of operations, liquidity, financial condition, financial strength, and debt ratings.

Insurers are subject to regulatory, political, and media scrutiny. We are subject to government market conduct reviews and investigations, legal actions, and penalties. There can be no assurance that our business will not be materially adversely

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affected by the outcomes of such activity in the future. If we are found to have violated laws and regulations, it could materially adversely affect our reputation, financial condition, and operating results.

Our business is subject to various state, federal, and other laws, rules, policies, and other data use and protection obligations.

We are subject to federal and state laws relating to collecting, using, retaining, securing, and transferring personally identifiable information ("PII"). Federal laws include the Gramm-Leach-Bliley Act, the Fair Credit Reporting Act, the Drivers Privacy Protection Act, the Health Insurance Portability and Accountability Act, and Unfair and Deceptive Acts and Practices laws. Several states, like New York, Nevada, Colorado, Virginia, and California, have passed similar laws, and others are considering imposing additional restrictions or creating new rights concerning PII. These laws continue to develop and may differ by jurisdiction. Complying with emerging and changing requirements may cause us to incur substantial costs or require us to change our business practices. Noncompliance could result in significant reputational harm, penalties, and legal liability.

General Data Protection Regulation ("GDPR") regulates data protection and privacy in the EU and personal data transfers outside the EU. GDPR’s main tenet is to give individuals primary control over their personal data. Because we do not write coverages in the EU, GDPR does not directly impact us. Some U.S. states have subsequently incorporated individual-control mechanisms into state privacy laws. Future EU data privacy actions likely will influence U.S. regulators over time.

We make statements about our use and disclosure of PII in our privacy notice, published on our website, and in other public venues. We could be subject to litigation or governmental actions if we fail to comply with these public statements or federal and state privacy-related and data protection laws and regulations. Such proceedings could impact our reputation and result in penalties, including ongoing audit requirements and significant legal liability.

We are engaged in ordinary routine legal proceedings incidental to our insurance operations that are inherently unpredictable and could impact our reputation and/or have a material adverse effect on our consolidated results of operations or cash flows in particular quarterly or annual periods.

We are engaged in ordinary routine legal proceedings incidental to our insurance operations that include:

•Indemnity or defense of third-party suits brought against our insureds;

•Defense of actions brought against us by our insureds who disagree with our coverage decisions, some of which allege bad faith claims handling and seek extra-contractual damages, punitive damages, or other penalties;

•Actions we file, primarily for declaratory judgment, seeking confirmation that we have made appropriate coverage decisions under our insurance contracts;

•Actions brought against competitors or us by plaintiffs alleging improper business practices and sometimes seeking class status. Such actions historically have included issues and allegations, without limitation, related to (i) unfairly discriminatory underwriting practices, including the impact of credit score usage, (ii) managed care practices, such as provider reimbursement, and (iii) automobile claims practices; and

•Actions we file against third parties and other insurers for subrogation and recovery of other amounts we paid on our insureds' behalf.

Some of our legal proceedings may receive media attention because of their perceived newsworthiness and/or relationship to various broad economic, political, social, and legal developments or trends. Such media stories could negatively impact our reputation.

We expect any potential ultimate liability for ordinary routine legal proceedings incidental to our insurance business will not be material to our consolidated financial condition after considering estimated loss provisions. Litigation outcomes are inherently unpredictable, even with meritorious defenses. The same is true with case-specific litigation duration, as state dockets are often overcrowded. Generally, the longer a case is in litigation, the more expensive it can become. Because the amounts sought in specific actions are large or indeterminate, any adverse outcomes could have a material adverse effect on our consolidated results of operations or cash flows in particular quarterly or annual periods.

We have no material litigation risks related to climate change.

Risks Related to Our Corporate Structure and Governance

We are a holding company, and our ability to declare dividends to our shareholders, pay indebtedness, and enter into affiliate transactions may be limited because our Insurance Subsidiaries are regulated.

Restrictions on our Insurance Subsidiaries' ability to pay dividends, make loans or advances to the Parent, or enter into

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transactions with affiliates may materially affect our ability to pay dividends on our preferred and common stock or repay our indebtedness. Based on these restrictions, there is a maximum ordinary annual dividend amount the Insurance Subsidiaries can provide the Parent. Our Insurance Subsidiaries' ability to pay dividends or make loans or advances is subject to the approval or review of our domiciliary state insurance regulators. For additional details regarding dividend restrictions, see Note 22. "Statutory Financial Information, Capital Requirements, and Restrictions on Dividends and Transfers of Funds" in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K.

The Parent’s ability to pay dividends to its stockholders is also impacted by covenants in its credit agreement (the "Line of Credit") among the Parent, the named lenders (the "Lenders"), and Wells Fargo Bank, National Association, as Administrative Agent. These covenants obligate the Parent to, among other things, maintain a minimum consolidated net worth and a maximum ratio of debt to capitalization. Our preferred stock's terms limit the Parent's ability to declare or pay dividends on, or purchase, redeem, or otherwise acquire shares of its common stock or any shares of the Parent that rank junior to, or on parity with, the preferred stock if the Parent does not declare and pay (or set aside) dividends on the preferred stock for the last preceding dividend period. For additional details about the Line of Credit's financial covenants, see Note 11. "Indebtedness" in Item 8. "Financial Statements and Supplementary Data" of this Form 10-K. For additional details about conditions related to our preferred stock, see Note 17. "Equity" in Item 8. "Financial Statements and Supplementary Data" of this Form 10-K.

Because we are a New Jersey corporation and an insurance holding company, we may be less attractive to potential acquirers and our common stock's value could be adversely affected.

We are a New Jersey company, and provisions of the New Jersey Shareholders' Protection Act and our Amended and Restated Certificate of Incorporation may discourage, delay, or prevent us from being acquired. A supermajority of our shareholders must approve (i) certain business combinations with interested shareholders or (ii) any amendment to the related provisions of our Amended and Restated Certificate of Incorporation unless certain conditions are met. These conditions may relate to, among other things, the interested stockholder's acquisition of stock, the approval of the business combination by disinterested members of our Board and disinterested stockholders, and the price and payment of the consideration proposed in the business combination. In addition to considering the effects of any action on our shareholders (including any offer or proposal to acquire the Parent), our Board may consider (i) the long-term, and short-term interests of the Parent and our shareholders, including the possibility that the Parent’s continued independence may best serve these interests, (ii) the effects of the action on the Parent's employees, suppliers, creditors, and customers, and (iii) the effects of the action on the community in which the Parent operates.

These provisions of our Amended and Restated Certificate of Incorporation and New Jersey law could (i) deprive our common shareholders of an opportunity to receive a premium over the prevailing market price in a hostile takeover and (ii) adversely affect the value of our common stock.

Because we own insurance subsidiaries, any party seeking to acquire 10% or more of our common stock must seek prior approval from the subsidiaries' domiciliary insurance regulators and file extensive information about their business operations and finances. The New Jersey Department of Banking and Insurance Commissioner, who regulates seven of our Insurance Subsidiaries, also considers whether (i) the acquisition of control of an insurer would be adverse to the public interest or the protection of existing and future policyholders or (ii) persons seeking control would use control adversely to the public interest or the protection of policyholders.

Risks Related to Our General Operations

We and our distribution partners and vendors are subject to attempted cyber-attacks and other cybersecurity and system availability risks.

Our business heavily relies on IT and application systems connected to or accessed through a connection to the Internet. Consequently, a malicious cyber-attack could affect us. Our systems also house proprietary and confidential information about our operations, employees, agents, and customers and their employees and property, including PII. A malicious cyber-attack on (i) our systems, (ii) our distribution partners or their key operating systems, and (iii) any other of our third-party partners or vendors and their key operating systems may interrupt our operations, damage our reputation and result in monetary damages that are difficult to quantify. These potential impacts from a malicious cyber-attack could have a material adverse effect on our results of operations, liquidity, financial condition, financial strength, and debt ratings.

Through encryption and authentication technologies, we have implemented system- and process-based risk mitigations intended to secure our IT systems and prevent unauthorized access to or loss of sensitive data. Cyber-attack sophistication evolves daily, so our security measures may not sufficiently address all eventualities. We may be vulnerable to hacking, employee error, malfeasance, system error, faulty password management, or other irregularities. We implement new technologies, including artificial intelligence, to increase operational efficiencies. These new technologies may increase the risk of cyber-attacks. We also rely on third-party technology providers whose cyber-attack risks may be higher or lower than ours depending on their

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profile and security program's maturity. To the extent possible and practical, we review third-party control environments, aligning the risk exposure with our business requirements and risk tolerances. Any disruption or breach of our systems or data security could damage our reputation, result in monetary damages that are difficult to estimate, and have a material adverse effect on our results of operations, liquidity, financial condition, financial strength, and debt ratings. To mitigate this risk, we have and expect to continue to (i) conduct disaster recovery exercises, employee education programs and tabletop exercises and (ii) develop and invest in a variety of controls to prevent, detect, and appropriately react to cyber-attacks, including frequently testing our systems' security and access controls. We have insurance coverage for certain cybersecurity risks, including privacy breach incidents, which may be insufficient to indemnify against all arising losses or types of claims.

In addition to the risk of cyber-attacks, we face system availability risk. Our business relies heavily on various IT and application systems. We have robust business continuity plans designed to minimize the duration and impact of an unexpected loss of availability of any of these systems. Nevertheless, we could experience an event that impacts one or more of these systems, including those based in facilities where our vendors or we operate. Such events could interrupt our ability to conduct business and negatively impact our results of operations, despite our business continuity plans.

Operational leverage necessitates the success of our risk management strategies, and their failure could have a material adverse effect on our financial condition or results of operations.

As an insurer, we assume risk from our policyholders. We define operating leverage as the ratio of NPW to our statutory surplus. We balance and mitigate our operational leverage risk with several risk management strategies within our insurance operations to achieve a balance of growth and profit, including an underwriting risk appetite focused on small-to-medium-sized accounts. We employ significant reinsurance, a disciplined reserving approach, and a conservative investment philosophy. These strategies have inherent limitations. We cannot be certain that an event or series of unanticipated events will not occur and result in greater than expected losses, which could have a material adverse effect on our results of operations, liquidity, financial condition, financial strength, and debt ratings.

Item 1B. Unresolved Staff Comments.

None.

Item 1C. Cybersecurity.

Risk Management and Strategy

Our business heavily relies on various IT and application systems that contain proprietary and confidential information about our operations, employees, agents, claimants, customers, and their employees and property, including personally identifiable information. These systems are connected to and/or accessed from the Internet, making them susceptible to cyber-attacks. A cyber-attack on our systems, distribution partners and their key operating systems, or any other third-party partners or vendors and their key operating systems may materially affect us. Potential impacts include prolonged interruption of our business operations, reputational harm, or substantial monetary damages. For a detailed description of the risks related to cybersecurity, refer to the "Risks Related to our General Operations" section in Item 1A. "Risk Factors." of this Form 10-K.

We have a dedicated unit, led by the Senior Vice President ("SVP") of IT Enterprise Strategy and Execution, to implement cybersecurity controls, assess and report on cybersecurity risks, and consult with our ERM unit, which is responsible for identifying, measuring, monitoring, and reporting on key enterprise-wide risks, including cybersecurity risks.

We work with industry-leading security consulting and technology partners and employ a "defense-in-depth" approach that uses multiple security measures to protect the integrity of our proprietary and confidential information. This approach aligns with the National Institute of Standards and Technology Cyber Security Framework and provides preventative, detective, and responsive measures to identify and manage risks. We periodically review our strategy and modify its implementation based on threat trends, program maturity, assessment results, and the advice of third-party security consultants. We have documented information security policies, procedures, and guidelines, known as our "Written Information Security Program." Our program (i) balances responsiveness to rapidly changing threats with ensuring our IT security environment's sustainability and overall effectiveness and (ii) is reasonably likely to defend against risks of cybersecurity threats that would have a material impact on our business strategy, results of operations, or financial condition. This program focuses on the following six key areas to monitor various IT performance and security metrics:

•Proactive cybersecurity processes, including vulnerability scanning, penetration testing, and periodic program assessments by outside security consultants and assessors;

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•Reactive cybersecurity processes that we regularly evaluate using incident response and disaster recovery exercises based on realistic scenarios;

•Endpoint technology that includes encryption, threat management, monitoring, investigation support, and backups;

•Identity and access management controls that often include multi-factor authentication and additional safeguards for staff granted elevated privileges;

•Employee cyber risk awareness, training, and testing that covers cybersecurity threats and actions to prevent or report attacks; and

•Third-party risk management and security standards, including due diligence, continuous monitoring, cyber risk scoring, and contractual obligations. We review third-party control environments when possible and practical, aligning the risk exposure with our business requirements and risk tolerances.

Board Governance and Management

The Executive Vice President ("EVP") & Chief Information Officer ("CIO") and the SVP of Enterprise Strategy and Execution provide quarterly written and in-person updates on the strength of our cyber risk control environment, emerging cyber threat issues, and the results of external assessments by outside security consultants and assessors to the Board’s Risk Committee. The Board's Risk Committee oversees our ERM framework and practices and assists the Board in overseeing our operational activities, including the Company's information technology security program, and identifying and reviewing related risks.

The cybersecurity team, managed by the SVP of IT Enterprise Strategy and Execution, (i) receives oversight and executive support through engagement with our ERC, which is responsible for the holistic evaluation, management, and supervision of our aggregate risk profile and (ii) collaborates with our ERM function on business alignment and cybersecurity insurance procurement.

The expertise of key members of management and our committees responsible for assessing, managing, and presenting quarterly updates to the Board’s Risk Committee about our cybersecurity risks is summarized as follows:

•John Bresney, EVP & CIO, reports directly to our Chief Executive Officer and is responsible for all of our IT operations, including oversight of the SVP of Enterprise Strategy and Execution’s implementation of our cybersecurity program and enforcement of our cybersecurity policies. He has worked for us for approximately 31 years, holding various technology and information security roles of increasing responsibility. He has a bachelor’s degree in information systems and business, a Master’s Certificate in Project Management, and a Columbia University CIO Program Certificate.

•Robert McKenna, SVP of Enterprise Strategy and Execution, reports to our CIO and leads the implementation of our cybersecurity program, enforcement of our cybersecurity policies, technology planning, projects driving IT strategy, and enterprise IT risk management. He also oversees cybersecurity incidents under our Security Incident Response Plan ("IRP"). He has worked for us for approximately 22 years in related positions of increasing responsibility and has over 28 years of technology and information security experience. He has a master’s degree in business administration, a Certificate in Project Management, and is a Certified Insurance Counselor.

•Christopher Cunniff, SVP and CRO, reports to our Chief Financial Officer, leads our Reinsurance and ERM teams, and chairs the ERC and the Market Security Committee. He has worked for us for approximately seven years, and he previously was our SVP of Actuarial Reserving. He has over 33 years of insurance industry experience, serving in various key leadership positions. He has a bachelor’s degree in mathematics, is a fellow of the Casualty Actuarial Society, and is a member of the American Academy of Actuaries.

Our IRP describes the circumstances that require internal and external notifications of cybersecurity incidents that (i) relate to any of our computer systems or networks and compromise the confidentiality, integrity, or availability of the systems or networks, (ii) compromise the confidentiality, integrity, or availability of any sensitive data that belongs to us or a third party and is in our care or custody, or (iii) involve one or more third parties with whom we share sensitive data. It describes the (i) involvement of the SVP of Enterprise Strategy and Execution, (ii) escalation process of such incidents to senior management,

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including the General Counsel, CIO, Chief Financial Officer, CRO, and Chief Executive Officer, (iii) reporting process to the Risk Committee and Board, and (iv) the notification and disclosure process to customers, distribution partners, regulators, and the SEC. The IRP also provides guidance on how to evaluate potential cyber events and suspicious cyber occurrences. We engage outside legal counsel and technical experts to regularly review the IRP and use internal teams and outside advisors with specialized skills to support the response and recovery efforts of proprietary and confidential information.

For additional information on our overall corporate governance structure and internal process of assessing our other significant risks, see the "Corporate Governance, Sustainability and Social Responsibility" section in Item 1. "Business." of this Form 10-K.

Item 2. Properties.

Our headquarters is a 315,000-square-foot building on an owned 56-acre site zoned for office and professional use in Branchville, New Jersey. We lease all our other operating facilities from unrelated parties. The principal office locations of our insurance operations are listed in the "Geographic Markets" section of Item 1. "Business." of this Form 10-K. Our Investments operations are principally located in leased space in Farmington, Connecticut. Our facilities provide adequate space for our present needs. Additional space should be available on reasonable terms if needed.

Item 3. Legal Proceedings.

We are routinely engaged in legal proceedings incidental to our insurance operations that have inherently unpredictable outcomes and could have a material adverse effect on our consolidated results of operations or cash flows in particular quarterly or annual periods. For additional information regarding our legal risks, refer to Item 1A. "Risk Factors." and Note 21. "Litigation" included in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K. As of December 31, 2024, we have no material pending legal proceedings that could have a material adverse effect on our consolidated financial condition, results of operations, or cash flows.

Item 4. Mine Safety Disclosures.

Not applicable.

PART II

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

(a) Market Information

Our common stock is traded on the Nasdaq Global Select Market under the symbol "SIGI."

(b) Holders

Our transfer agent’s records reflect that we had 2,720 common stockholders of record as of January 31, 2025.

Dividends on shares of our common stock are declared and paid at the discretion of the Board of Directors (the "Board") based on our results of operations, financial condition, capital requirements, contractual restrictions, and other relevant factors. We expect to continue to pay quarterly cash dividends on shares of our common stock.

In the fourth quarter of 2024, the Board approved a 9% increase in our common stock dividend to $0.38 per share. The Board declared a $0.38 per share quarterly cash dividend on common stock payable March 3, 2025, to stockholders of record as of February 14, 2025.

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(d) Securities Authorized for Issuance under Equity Compensation Plans

The following table provides information about our common stock authorized for issuance under equity compensation plans as of December 31, 2024:

(a) (b) (c)

Equity compensation plans approved by security holders — $ — 4,411,194

1Includes 975,358 shares available for issuance under our Employee Stock Purchase Plan (2021); 1,466,600 shares available for issuance under the Stock Purchase Plan for Independent Insurance Agencies; and 1,969,236 shares for issuance under the Selective Insurance Group, Inc. 2024 Omnibus Stock Plan ("Stock Plan"). Future grants under the Stock Plan can include stock options, restricted stock units, or restricted stock.

(e) Performance Graph

The following chart, produced by Research Data Group, Inc., depicts our performance for the period beginning December 31, 2019, and ending December 31, 2024, comparing total stockholder return on our common stock to the total return of (i) the NASDAQ Composite Index and (ii) a select group of peer companies comprised of NASDAQ-listed companies in SIC Code 6330-6339, Fire, Marine, and Casualty Insurance.

We have not incorporated this performance graph into any other filings we have made with the SEC. Unless we specifically state otherwise, it will not be incorporated by reference into any future SEC filings. This performance graph shall not be deemed "soliciting material" or be "filed" with the SEC unless we specifically request so or incorporate it by reference in any SEC filings we make.

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(f) Purchases of Equity Securities by the Issuer and Affiliated Purchasers

The following table provides information about our purchases of our common stock in the fourth quarter of 2024:

1We purchased these shares from employees to satisfy tax withholding obligations associated with the vesting of their restricted stock units.

2On December 2, 2020, we announced our Board authorized a $100 million share repurchase program with no set expiration or termination date. Our repurchase program does not obligate us to acquire any particular amount of our common stock. Management will determine the timing and amount of any share repurchases under the authorization at its discretion based on market conditions and other considerations.

Item 6. Reserved.

Not applicable.

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

Forward-Looking Statements

The terms "Company," "we," "us," and "our" refer to Selective Insurance Group, Inc. (the "Parent") and its subsidiaries, except as expressly indicated or the context otherwise requires. Certain statements in this Annual Report on Form 10-K, including information incorporated by reference, are “forward-looking statements” defined in the Private Securities Litigation Reform Act of 1995 ("PSLRA"). The PSLRA provides a forward-looking statement safe harbor under the Securities Act of 1933 and the Securities Exchange Act of 1934. These statements discuss our intentions, beliefs, projections, estimations, or forecasts of future events and financial performance. They involve known and unknown risks, uncertainties, and other factors that may cause our or our industry's actual results, activity levels, or performance to materially differ from those in or implied by the forward-looking statements. In some cases, forward-looking statements include the words "may," "will," "could," "would," "should," "expect," "plan," "anticipate," "attribute," "confident," "strong," "target," "project," "intend," "believe," "estimate," "predict," "potential," "pro forma," "seek," "likely," "continue," or comparable terms. Our forward-looking statements are only predictions; we cannot guarantee or assure that such expectations will prove correct. We undertake no obligation to publicly update or revise any forward-looking statements for any reason except as required by law.

We discuss the factors that could cause our actual results to differ materially from our projections, forecasts, or estimates in forward-looking statements in Item 1A. "Risk Factors." of this form 10-K. These risk factors may not be exhaustive. We operate in a constantly changing business environment, and new risk factors may emerge anytime. We cannot predict these new risk factors, their impact on our businesses, or the extent to which one or any combination of factors may cause actual results to differ materially from any forward-looking statements. Given these risks, uncertainties, and assumptions, the forward-looking events we discuss might not occur.

Introduction

We classify our business into four reportable segments:

•Standard Commercial Lines;

•Standard Personal Lines;

•Excess and Surplus Lines ("E&S Lines"); and

•Investments.

For more details about these segments, refer to Note 1. "Organization" and Note 12. "Segment Information" in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K.

We write our Standard Commercial and Standard Personal Lines products and services through nine of our insurance subsidiaries, some of which participate in the federal government's National Flood Insurance Program's ("NFIP") Write Your Own Program ("WYO"). We write our E&S products through another subsidiary, Mesa Underwriters Specialty Insurance Company ("MUSIC"), a nationally-authorized non-admitted platform for customers who generally cannot obtain coverage in the standard marketplace. Collectively, we refer to our ten insurance subsidiaries as the "Insurance Subsidiaries."

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The following is Management's Discussion and Analysis ("MD&A") of our financial condition and consolidated results of operations, including an evaluation of the amounts and certainty of cash flows from operations and outside sources, trends, and uncertainties that may have a material impact in future periods. The MD&A discusses and analyzes our 2024 results compared to 2023. Investors should read the MD&A in conjunction with Item 8. "Financial Statements and Supplementary Data." of this Form 10-K. For discussion and analysis of our 2023 results compared to 2022, refer to Item 7. "Management’s Discussion and Analysis of Financial Condition and Results of Operations." of our Annual Report on Form 10-K for the fiscal year ended December 31, 2023.

In the MD&A, we will discuss and analyze the following:

•Critical Accounting Policies and Estimates;

•Financial Highlights of Results for Years Ended December 31, 2024, 2023, and 2022;

•Results of Operations and Related Information by Segment;

•Federal Income Taxes; and

•Liquidity and Capital Resources.

Critical Accounting Policies and Estimates

We have identified the policies and estimates critical to our business operations and understanding of our results of operations. We consider the policies and estimates most critical to the preparation of the Financial Statements to be (i) reserve for loss and loss expense, (ii) investment valuation and the allowance for credit losses on available-for-sale ("AFS") fixed income securities, and (iii) reinsurance.

Reserve for Loss and Loss Expense

Significant time can elapse between the occurrence of an insured loss, the reporting of a claim to us, and the final claim settlement and payment. Insurers establish reserves as balance sheet liabilities to recognize liabilities for unpaid loss and loss expenses. The following tables provide case and incurred but not reported ("IBNR") reserves for loss and loss expenses and reinsurance recoverable on unpaid loss and loss expense as of December 31, 2024 and 2023:

December 31, 2024 Loss and Loss Expense Reserves

1Includes our flood loss exposure related to our participation in the NFIP's WYO program, to which we cede 100% of our WYO flood losses.

2Includes general liability (97% of net reserves) and commercial auto liability coverages (3% of net reserves).

3Includes commercial property (93% of net reserves) and commercial auto property coverages (7% of net reserves).

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December 31, 2023 Loss and Loss Expense Reserves

1Includes our flood loss exposure relates to our participation in the NFIP's WYO program, to which we cede 100% of our flood losses.

2Includes general liability (97% of net reserves) and commercial auto liability coverages (3% of net reserves).

3Includes commercial property (90% of net reserves) and commercial auto property coverages (10% of net reserves).

The Insurance Subsidiaries' net loss and loss expense reserves duration was approximately 3.0 years at December 31, 2024 and 3.1 years at December 31, 2023.

How the reserve is established

Reserve for loss and loss expense include case reserves on reported claims and IBNR reserves. Case reserves are estimated for each individual claim based on facts and circumstances known at the time. Case reserves may be adjusted up or down as the claim's specific facts and circumstances change. IBNR reserves are established at more aggregated levels and include provisions for (i) claims not yet reported, (ii) future development on reported claims, (iii) closed claims that could reopen in the future, and (iv) anticipated salvage and subrogation recoveries.

We perform quarterly internal reserve reviews using our own loss experience, considering various internal and external factors. Changes in claim dynamics may inherently alter paid and reported development patterns. While the selections in our reserve analyses aim to account for these impacts, estimated reserves involve greater risk of variability. In addition to our internal reserve reviews, an external consulting actuary performs an independent semiannual reserve review. We do not rely on the external consulting actuary's report to determine our recorded reserves but we review and discuss our observations on trends, key assumptions, and actuarial methodologies with our consulting actuary. While not required, our independent consulting actuary issues the annual statutory Statements of Actuarial Opinion for our Insurance Subsidiaries. For additional information on our accounting policy for reserve for loss and loss expense, refer to Note. 2. "Summary of Significant Accounting Policies" in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K.

Range of Reasonable Reserve Estimates

We have estimated a range of reasonable reserve estimates for net loss and loss expense of $5,003 million to $6,114 million at December 31, 2024. This range reflects low and high reasonable reserve estimates determined after using judgment to adjust the methods, factors, and assumptions selected within the internal reserve review. This approach produces a range of reasonable reserve estimates but does not represent a distribution of all possible outcomes. Consequently, final outcomes may be greater or less than the estimates.

The range of reasonable reserve estimates increased as of December 31, 2024, relative to December 31, 2023. This increase was primarily related to reserve growth commensurate with (i) our net premiums earned ("NPE") growth and (ii) increased uncertainty in severity due to the impact of social inflation.

Changes in Reserve Estimates (Loss Development)

Our quarterly reserving process may lead to changes in the recorded reserves for prior accident years, referred to as favorable or unfavorable prior year loss and loss expense development. In 2024, we experienced net unfavorable prior year loss

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development of $285.3 million, compared to net unfavorable development of $10.0 million in 2023 and net favorable development of $78.9 million in 2022. The following table summarizes prior year development by line of business:

(Favorable)/Unfavorable Prior Year Loss and Loss Expense Development

Businessowners' policies (1.7) 7.6 (7.3)

Commercial property (23.4) 0.7 (1.6)

E&S property lines (4.9) (1.6) (2.5)

A detailed discussion of recent reserve development by line of business follows.

Standard Market General Liability Line of Business

At December 31, 2024, our general liability line of business had recorded reserves, net of reinsurance, of $2.5 billion, representing 45% of our total net reserves. In 2024, this line experienced unfavorable reserve development of $316.0 million, primarily due to the impact of social inflation that increased loss severities in accident years 2020 and subsequent, with most of the actions for accident years 2022 and 2023. We attribute the increased severities to elevated social inflation, which we view as an industry dynamic characterized by higher claimant propensity for attorney representation and litigation, longer settlement times, and higher settlement values. Similarly, this line experienced unfavorable development in 2023 of $55.0 million, attributable to the impact of social inflation driving increased loss severities in accident years 2015 through 2020.

This general liability line of business has experienced a long-term historical trend of meaningful claim severity increases that have been partially offset by claim frequency decreases. In recent years, we have been embedding higher severity assumptions in our initial loss ratio estimates to address social inflation's increasing impacts. Although we planned for higher expected loss trends, 2024's claim emergence exceeded our expectations. If the favorable frequency trend moderates or severities continue to emerge higher than expected, this line's ultimate loss estimates could be adversely impacted.

The general liability line of business presents a diverse set of exposures. Various factors influence losses and loss trends, including legislative enactments, judicial decisions, and economic and social inflation. Economic inflation directly impacts our claims severities by increasing the costs of raw materials, medical procedures, and labor. Social inflation may impact both claim frequency and severity by affecting (i) claimant propensity to file a claim, (ii) the percentage of claimants who engage lawyers, and (iii) broader liability interpretations and the nature and amounts of judicial verdicts and associated awards, all influencing future settlement values. We monitor claim litigation rates regularly. We have observed the percentage of general liability claims with plaintiff attorney involvement increasing in recent periods. Other social inflationary factors, including the increased prevalence of third-party litigation funding, claimant willingness to undergo surgery, evolving plaintiff attorney strategies and tactics, and broadening liability definitions and interpretations are also impacting claims severities. These trends and post-pandemic court case scheduling continue to affect claim settlement times.

We have exposure to abuse or molestation claims, mainly through policies that we (i) underwrite through our Community and Public Services ("CAPS") strategic business unit and (ii) issue to schools, religious institutions, day-care facilities, and other social services. These CAPS business unit customers represented approximately 10% of our total Standard Commercial Lines NPW in 2024 and 2023. We continue to actively manage policy limits and monitor each jurisdiction's statute of limitations to ensure our rate level reflects increased exposure to the extent regulatorily possible. These underwriting and pricing actions have positioned the portfolio for future profitability but limited our CAPS growth in recent years.

Certain states have enacted state laws that extend the statute of limitations or permit windows for abuse or molestation claims and lawsuits that statutes of limitations previously barred. Consequently, we may receive claims decades after the alleged acts involving complex claims coverage determinations, potential litigation, higher defense costs, and the need to collect from reinsurers under older reinsurance agreements. Our claims and actuarial departments actively monitor these claims to identify changes in frequency or severity and any emerging or shifting trends.

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Our active monitoring of claim patterns and emerging or shifting trends should help us better understand this rapidly evolving exposure. However, the ultimate impact of social, political, and legal trends remains highly uncertain and could substantially impact the ultimate settlement values for these claims.

In addition, over the last several years, we have implemented underwriting changes within this line of business that we believe will lead to improved profitability. These changes may impact portfolio composition and may affect paid and reported development patterns. While our reserve analyses incorporate methods that adjust for these changes, our estimated reserves have a greater risk of fluctuation.

Standard Market Workers Compensation Line of Business

At December 31, 2024, our workers compensation line of business had recorded reserves, net of reinsurance, of $797 million, representing 14% of our total net reserves. During 2024, this line experienced favorable reserve development of $45.0 million, primarily due to improved loss severities in accident years 2022 and prior. Similarly, this line experienced favorable reserve development during 2023 of $74.5 million, primarily due to improved loss severities in accident years 2021 and prior. During both 2024 and 2023, the lower-than-expected loss emergence was partly due to (i) lower than initially anticipated medical inflation and (ii) our various implemented claims initiatives. Because of the length of time injured workers can receive related medical treatment, decreases in medical inflation can cause favorable loss development over an extended number of accident years.

A variety of issues can impact the workers compensation line of business, including:

Unexpected changes in medical cost inflation – The industry has experienced an extended period of lower medical claim cost inflation. Changes to our historical workers compensation medical costs and potential changes in future medical inflation could increase reserve variability;

Changes in statutory workers compensation benefits – Statutory benefit changes may affect all outstanding claims, including past and not-yet-settled claims. Depending on the social and political climate, these changes may either increase or decrease associated claim costs; and

Changes in utilization of the workers compensation system –These changes may be driven by economic, legislative, or other changes, like increased use of prescriptions for pharmaceuticals, more complex medical procedures, changes in permanently injured workers' life expectancy, and health insurance availability.

Standard Market Commercial Automobile Line of Business

At December 31, 2024, our commercial automobile line of business had recorded reserves, net of reinsurance, of $1.1 billion, representing 20% of our total net reserves. In 2024, this line experienced unfavorable prior year reserve development of $19.5 million, primarily due to increased severities in accident year 2023. In 2023, this line experienced unfavorable prior year reserve development of $8.0 million, driven by increased loss expenses in accident years 2022 and prior.

The commercial automobile line has experienced unfavorable trends in recent years that have negatively affected the industry's results and ours. During the pandemic, reduced frequencies were accompanied by significant severity increases, resulting from increased risky driving behaviors, such as speeding, distracted driving, and driving under the influence. Risky driving behaviors and the impacts of social inflation continue to pressure this line's claim severities. As of year-end 2024, frequencies remained somewhat below pre-pandemic levels due to changes in commuting patterns.

Increased property damage and physical damage severities relate to (i) elevated repair costs for increasingly complex vehicles that incorporate more technology, (ii) extended periods of rental reimbursement costs for claims, and (iii) inflationary impacts and disruptions to the supply chain, although these have moderated since their peak in 2022.

Over the last several years, we have implemented underwriting changes within this line of business that we believe will lead to improved profitability. These changes may impact portfolio composition and may affect paid and reported development patterns. While our reserve analyses incorporate methods that adjust for these changes, our estimated reserves have a greater risk of fluctuation.

Standard Market Personal Automobile Line of Business

At December 31, 2024, our personal automobile line of business had recorded reserves, net of reinsurance, of $158 million, representing 3% of our total net reserves. This line experienced unfavorable prior year reserve development of $11.1 million in 2024, primarily due to increased loss severities in accident years 2022 through 2023. This line experienced unfavorable prior year reserve development of $15.3 million in 2023, primarily due to increased loss severities in accident year 2022.

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Some of the same issues affecting the commercial automobile line also impact this line. The COVID-19-related frequency reduction was even more pronounced for the personal automobile line. Frequencies rebounded after the pandemic and now are at pre-pandemic levels. In addition to the COVID-19-related temporary impacts, the underlying trends of increased vehicle repair costs are likely causes of rising severities, exacerbated by riskier driving behaviors, including distracted driving. We continue recalibrating our predictive models and refining our underwriting and pricing approaches, including prioritizing additional rate filings by state and further refining our pricing factors. These filed rate increases began to take effect early in 2023 and increased in volume and magnitude throughout 2023 and 2024. We expect them to remain above loss trends in 2025 but lower than the rate increases in 2023 and 2024. While we believe these underwriting and pricing changes will ultimately lead to improved profitability and greater stability, the resulting changes to our exposure profile may impact paid and reported development patterns, increasing reserve uncertainty in the near term.

E&S Casualty Lines of Business

At December 31, 2024, our E&S casualty lines of business had recorded reserves, net of reinsurance, of $617 million, representing 11% of our total net reserves. In 2024, this line experienced unfavorable prior year reserve development of $20.0 million, primarily due to increased loss severities in accident years 2023 and prior. In 2023, this line experienced favorable prior year reserve development of $5.0 million, primarily due to improved loss severities in accident years 2021 and prior.

Some of the risk factors for the general liability line also affect the E&S casualty lines. These include (i) economic inflation, such as materials and labor costs and (ii) social inflationary trends, such as increased attorney involvement, broader liability findings, and more generous settlement awards. In response to these social inflationary trends, we have been embedding higher severity assumptions in our initial loss ratio estimates, which materialized in 2024.

Over the past several years, we have made operational changes to improve E&S casualty claims processes:

•We created a dedicated E&S claims team, bringing greater expertise and consistency to E&S claims handling.

•We created separate specialized claims teams for "litigated," "non-litigated," and "high exposure" claims.

•We implemented legal operational and expense improvement initiatives, including (i) increasing the use of employed staff counsel lawyers to defend covered claims litigation and (ii) consistent with our duty to defend and manage litigation against our policyholders per the terms and conditions of our policies, we enhanced processes for legal budgeting, expense management, and selection and evaluation of outside policyholder defense counsel.

While we believe these claims operational changes are improving our results and customer experience, they have inherent risks. Changes in claims processes may affect paid and reported development patterns. Our reserve analyses incorporate methods that adjust for these changes, but our estimated reserves have a greater risk of fluctuation.

Other impacts that create additional loss and loss expense reserve uncertainty

Claims Initiative Impacts

Our Claims Department continually identifies areas for improvement and efficiency to increase our policyholder value proposition. These improvements may lead to changes in claims practice that affect average case reserve levels and claims settlement rates, which directly impact the data we use to project ultimate loss and loss expense. While these changes may increase uncertainty in our estimates in the short term, we expect refined claims process management to create longer-term benefits.

Our internal reserve analyses incorporate actuarial projection methods that make adjustments for changes in case reserve adequacy and claims settlement rates. These methods adjust our historical loss experience to the current case adequacy or settlement rate level, providing a more consistent basis for projecting future development patterns. Because these projection methods have their own assumptions and judgments, no single method can be considered definitive.

Unanticipated Changes in Economic Inflation

United States ("U.S.") fiscal and monetary policy and global economic conditions bring additional inflationary trend uncertainty. Changes in inflation affect the ultimate settlement costs for many of our lines of business, with the greatest reserve impact on the longer-tailed lines, such as general liability and workers compensation. Uncertainty about future inflation or deflation creates the potential for additional reserve variability in these lines of business.

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Sensitivity analysis: Potential impact on reserve estimates due to changes in key assumptions

Our process to establish reserves includes a variety of key assumptions, such as:

•The selection of loss and loss expense development factors;

•The weight applied to each individual actuarial projection method;

•Projected future loss trends; and

•Expected claim frequencies, severities, and ultimate loss and loss expense ratios for the current accident year.

The importance of any single assumption depends on several considerations, such as line of business and accident year. If the actual experience emerges differently than the assumptions underlying the reserve process, possible changes in our reserve estimates could be material to the results of operations in future periods. We conduct sensitivity tests highlighting potential impacts to loss and loss expense reserves for the major casualty lines of business under different scenarios. These tests consider each assumption and line of business individually without considering correlation between lines of business and accident years. The results (i) do not constitute an actuarial range, (ii) show possible impacts from variations in certain key assumptions, and (iii) offer no assurance that future loss and loss expense emergence will be consistent with our current or alternative assumptions.

Changes in internal and external trends and operational changes may manifest as changes in loss and loss expense development patterns. These patterns are a key assumption in the reserving process, as are the current accident year expected loss and loss expense ratios. These ratios are developed through a rigorous process of projecting recent accident years' experience to an ultimate settlement basis. They then are adjusted to the current accident year's pricing and loss cost levels. The impact of underwriting portfolio and claims handling practice changes is also quantified and reflected where appropriate. Nonetheless, the ultimate loss and loss expense ratios may differ from current estimates.

The two tables below illustrate the sensitivities of loss and loss expense reserves to these key assumptions for the major casualty lines. The first table displays estimated impacts from changes in expected reported loss and loss expense development patterns for our major casualty lines of business. It shows line of business reserve impacts if the actual calendar year incurred amounts are greater or less than current expectations by the selected percentages. While judgmental, the selected percentages by line are based on the reserve range analysis and the actual historical reserve development for the line of business. The second table displays the estimated impacts of changes to the expected loss and loss expense ratios for the current accident year. It shows reserve impacts by line of business if the expected loss and loss expense ratios for the current accident year are greater or less than current expectations by the selected percentages.

Reserve Impacts of Changes to Expected Loss and Loss Expense Reporting Patterns

Workers compensation 15 (85) 85

Commercial automobile liability 10 (110) 110

Personal automobile liability 15 (20) 20

Workers compensation 10 (35) 35

Commercial automobile liability 10 (75) 75

Personal automobile liability 15 (20) 20

There is some overlap between the impacts shown in the tables. For example, increases in the calendar year development would ultimately impact our view of the current accident year's loss and loss expense ratios. However, these tables provide perspective on the sensitivity of each key assumption. While the changes represent outcomes based on reasonably likely changes to our underlying reserving assumptions, they do not represent a range of possible outcomes and our reserves could increase or decrease significantly differently.

Asbestos and Environmental Reserves

Our general liability, businessowners' policies, and homeowners reserves include exposure to asbestos and environmental claims. The emergence of these claims occurs over an extended period and can be unpredictable. The total recorded net loss

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and loss expense reserves for these claims were $27.4 million as of December 31, 2024, and $19.1 million as of December 31, 2023, with asbestos claims constituting approximately 44% of these reserves in 2024 and 18% in 2023.

Environmental claims have arisen primarily from Standard Commercial Lines policies issued to municipal governments and small non-manufacturing commercial customers for landfill exposures, and Standard Personal Lines homeowners policies related to leaking underground storage tanks. Asbestos claims have arisen primarily from Standard Commercial Lines policies issued to (i) various distributors of asbestos-containing products, such as electrical and plumbing materials and (ii) contractors exposed to or handling asbestos-containing products, such as heating, ventilation, and air conditioning contractors. These claims are handled in a centralized and specialized asbestos and environmental claim unit that establishes case reserves based on each claim's then-known facts and circumstances, which IBNR reserves supplement.

Estimating IBNR reserves for asbestos and environmental claims is difficult because these claims have delayed and inconsistent reporting patterns. Significant uncertainties are associated with estimating critical reserve assumptions, such as average clean-up costs, third-party costs, potentially responsible party shares, allocation of damages, litigation and coverage costs, and potential state and federal legislative changes.

Other Latent Exposures

We have other latent and continuous trigger exposures in our ongoing portfolio. Examples include claims for construction defect and abuse or molestation, including in states that have increased and expanded the statute of limitations. We manage our exposure to these liabilities through our underwriting and claims practices, which includes a dedicated claims unit, like we do for asbestos and environmental claims. The impact of social, political, and legal trends on these claims remains highly uncertain, so the development and adequacy of our related loss and loss expense reserves remain highly uncertain. Some of these exposures remain in our ongoing portfolio and are reserved in aggregate, with other exposures within the line of business reserves. We remove other unusual and highly uncertain exposures, like toxic product claims involving diacetyl, lead paint, and silica, from our traditional reserve analysis and undertake a separate review for them.

Investment Valuation and the Allowance for Credit Losses on AFS Fixed Income Securities

Investment Valuation

Accounting guidance defines the fair value of our investment portfolio as the exit price or amount that would be (i) received to sell an asset or (ii) paid to transfer a liability in an orderly transaction between market participants. When determining an exit price, we must rely on observable market data, if available. Most securities in our equity portfolio have readily determinable fair values and are recorded at fair value with changes in unrealized gains or losses recognized through income. Our AFS fixed income securities portfolio is recorded at fair value, and the related unrealized gains or losses are reflected in stockholders' equity, net of tax. For our AFS fixed income securities portfolios, fair value is a key factor in the measurement of (i) losses on securities for which we have the intent to sell and (ii) changes in the allowance for credit losses.

The fair value of approximately 91% of our investments measured at fair value are classified as either Level 1 or Level 2 in the fair value hierarchy and are priced using observable inputs for identical or similar assets. About 9% are classified as either (i) Level 3 and are based on unobservable market inputs because the related securities are not traded on a public market, or (ii) not leveled because the related securities are measured at fair value using net asset value per share (or its practical expedient). For additional information, refer to the following sections within Item 8. "Financial Statements and Supplementary Data." of this Form 10-K: (i) item (d) of Note 2. "Summary of Significant Accounting Policies" for descriptions of the levels within the fair value hierarchy and the valuation techniques used for our Level 3 securities, and (ii) Note 7. "Fair Value Measurements" for quantitative information on the unobservable inputs in our securities measured using Level 3 inputs.

Allowance for Credit Losses on AFS Fixed Income Securities

When fixed income securities are in an unrealized loss position and we do not intend to sell them, we record an allowance for credit losses for the portion of the unrealized loss related to an expected credit loss. We estimate expected credit losses on these securities by performing a risk-adjusted discounted cash flow ("DCF"). The allowance for credit losses is the excess of amortized cost over the greater of (i) our estimate of the present value of expected future cash flows or (ii) fair value. The allowance for credit losses cannot exceed the unrealized loss, and therefore it may fluctuate with changes in the security's fair value. We also consider the need to record losses on securities in an unrealized loss position for which we have the intent to sell. If we determine that we have the intent or likely requirement to sell the security, we write down its amortized cost to its fair value.

We analyze unrealized losses for credit loss in accordance with our existing accounting policy, which includes performing DCF analyses on securities at the lot level and analyzing these DCFs using various economic scenarios. In performing these DCF analyses, we calculate the present value of future cash flows using various models specific to the major security types in our

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portfolio. These models use security-specific information and forecasted macroeconomic data to determine possible expected credit loss scenarios based on projected economic changes. The forecasted economic data incorporated into the models is based on the Federal Reserve Board’s annual supervisory stress test review on certain large banks and financial institutions.

We also can incorporate internally-developed forecast information into the models as we deem appropriate. In developing our best estimate of the allowance for credit losses, we consider our outlook on the probability of the various scenarios occurring.

Based on these analyses, we recorded an allowance for credit losses on our AFS fixed income securities portfolio of $31.9 million at December 31, 2024, and $28.2 million at December 31, 2023. If the security-specific and macroeconomic assumptions in our DCF analyses or our outlook on the occurrence probability of our DCF model scenarios were to change, our allowance for credit losses and the resulting credit loss expense or benefit will negatively or positively impact our results of operations. Factors considered in determining the allowance for credit losses require significant judgment, including our evaluation of the security's projected cash flow stream.

For additional information regarding our allowance for credit losses on AFS fixed income securities, see item (c) of Note 2. "Summary of Significant Accounting Policies" and item (i) of Note 5. "Investments" within Item 8. "Financial Statements and Supplementary Data." of this Form 10-K, respectively.

Reinsurance

Reinsurance recoverables on paid and unpaid loss and loss expense represent our estimates of the amounts we will recover from reinsurers. Each reinsurance contract is analyzed to ensure sufficient risk is transferred to record the transactions appropriately as reinsurance in the Financial Statements. Amounts recovered from reinsurers are recognized as assets contemporaneously and in a manner consistent with the paid and unpaid losses associated with the underlying policies. An allowance for credit losses on our reinsurance recoverable balance is recorded based on an evaluation of balances due from reinsurers and other available information, including collateral we hold under the terms and conditions of the underlying agreements. Reinsurers often purchase and rely on their retrocessional reinsurance programs to manage their capital position and improve their financial strength ratings. Details about retrocessional reinsurance programs are not always transparent, making it difficult to assess our reinsurers' exposure to counterparty credit risk. Other factors impact our reinsurer's credit quality, such as their reserve adequacy, investment portfolio, regulatory capital position, catastrophe aggregations, and risk management practices. In addition, contractual language interpretations and willingness to pay valid claims can impact our allowance for estimated uncollectible reinsurance. Our allowance for estimated uncollectible reinsurance was $2.0 million at December 31, 2024, and $1.7 million at December 31, 2023. We continually monitor developments that may impact recoverability from our reinsurers, for which we have contractual remedies, if necessary. For further information regarding reinsurance, see the "Reinsurance" section below in "Results of Operations and Related Information by Segment" and Note 9. "Reinsurance" in Item 8. "Financial Statements and Supplementary Data." of this Form 10-K.

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Financial Highlights of Results for Years Ended December 31, 2024, 2023, and 20221

Financial Data:

Key Metrics:

Net premiums written to statutory surplus ratio $ 1.60 1.51 6 % $ 1.44 5 %

Per Common Share Amounts:

Diluted net income (loss) per share $ 3.23 5.84 (45) % $ 3.54 65 %

Dividends declared per share to common stockholders 1.43 1.25 14 1.14 10

Non-GAAP Information2:

Non-GAAP operating income (loss) per diluted common share 3.27 5.89 (44) 5.03 17

1Refer to the Glossary of Terms attached to this Form 10-K as Exhibit 99.1 for definitions of terms used in this financial review.

2Non-GAAP operating income (loss), non-GAAP operating income (loss) per diluted common share, and non-GAAP operating ROE are comparable to net income (loss) available to common stockholders, net income (loss) available to common stockholders per diluted common share, and ROE, respectively, but exclude after tax net realized and unrealized gains and losses on investments included in net income (loss). Adjusted book value per common share is comparable to book value per common share, but excludes total after-tax unrealized gains and losses on investments included in accumulated other comprehensive income (loss). These non-GAAP measures are important financial measures used by us, analysts, and investors because the timing of realized and unrealized investment gains and losses on securities in any given period is largely discretionary. In addition, net realized and unrealized investment gains and losses on investments could distort the analysis of trends.

Reconciliations of our GAAP to non-GAAP measures are provided in the tables below:

Non-GAAP operating income (loss) per diluted common share $ 3.27 5.89 5.03

Reconciliation of ROE to non-GAAP operating ROE 2024 2023 2022

Tax on reconciling items — — (1.1)

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The components of our ROE and non-GAAP operating ROE are as follows:

Standard Commercial Lines segment (4.0) % 5.0 (9.0) pts 4.6 0.4 pts

Standard Personal Lines segment (1.1) (2.5) 1.4 (0.2) (2.3)

Total insurance operations (3.7) 4.2 (7.9) 5.4 (1.2)

Net realized and unrealized investment gains (losses) (0.1) (0.1) — (3.6) 3.5

In 2024, we generated an ROE of 7.0% compared to 14.3% in 2023. Our non-GAAP operating ROE of 7.1% in 2024 was below our target non-GAAP operating ROE of 12% and below our 2023 non-GAAP operating ROE of 14.4%. Investment performance was strong in 2024 and contributed 12.8 points to ROE; however, an after-tax underwriting loss reduced our ROE by 3.7 points in 2024, a reduction of 7.9 points when compared to 2023.

The after-tax underwriting loss in 2024 compared to income in 2023 was primarily attributable to unfavorable prior year casualty reserve development in 2024. We recorded $311.0 million of unfavorable prior year casualty reserve development in 2024, compared to $6.5 million of favorable prior year casualty reserve development in 2023. Development in 2024 included $316.0 million in the general liability line of business in our Standard Commercial Lines segment for accident years 2020 and subsequent, with most of the actions for accident years 2022 and 2023. We believe that current market conditions and environmental factors, most notably social inflation, are impacting us more than historically. As a commercial lines-focused underwriter with a higher mix of casualty business, we recognize this social inflationary environment has increased loss severities. Reflecting these trends, current year casualty loss costs were 1.4 combined ratio points higher in 2024 compared to 2023.

For additional qualitative discussion on prior year casualty reserve development, refer to the insurance segment sections below.

Outlook

Although our 2024 ROE was below our target, we ended the year with a strong capital position and the financial flexibility to execute our strategy of disciplined, profitable growth. In recent years, we made strategic investments to expand our runway for profitable growth. These included adding eight states to our Standard Commercial Lines footprint, organically growing within our existing footprint, and investing in technology. These investments better position us to scale our business effectively with a focus on operational efficiency. Our reserving actions, pricing response, and progress on our strategic priorities in 2024 have us well-positioned to quickly return to delivering operating ROEs at or better than our 12% target.

Our granular approach to managing renewal pure price and retention coupled with our unique field model, the strength of our distribution partner relationships, and focus on customer experience continue to differentiate us in the market. In this uncertain environment, we are focused on rate and non-rate actions to drive underwriting profitability while prudently growing the business, including:

•Standard Commercial Lines

◦Achieving overall Standard Commercial Lines renewal pure price increases that reflect forward loss trend expectations;

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◦Implementing underwriting refinements in our general liability line of business, including managing limits and coverage grants in challenging jurisdictions, driving improved terms and conditions, and focusing production on better-performing classes of business;

◦Continuing to expand our Standard Commercial Lines market share by (i) increasing our share towards a 12% target of our agents' premiums and (ii) strategically appointing new agents; and

◦Expanding our geographic footprint. In 2024, we entered Maine, Nevada, Oregon, Washington, and West Virginia, now covering 35 states and the District of Columbia. We expect to write new business in Kansas, Montana, and Wyoming over the next two years. After that, our pace of geographic expansion should moderate as we move closer to our goal of operating our Standard Commercial Lines business with a near national footprint.

•Standard Personal Lines

◦Continuing to refine our underwriting approach and pricing factors and achieving overall Standard Personal Lines renewal pure price increases that exceed loss trends;

◦Continuing to grow our mass affluent customer base in states where we have filed and obtained approvals of adequate rates; and

◦Continuing to seek improved homeowners line of business profitability by expanding the use of new policy terms and conditions, including (i) coverage for older roofs based on depreciation schedules rather than replacement cost and (ii) implementing mandatory wind/hail deductibles in states exposed to severe convective storms, where law permits.

•E&S Lines

◦Achieving E&S Lines renewal pure price increases that reflect forward loss trend expectations; and

◦Continuing to invest in product expansion, risk evaluation, and operational efficiency for small and middle market E&S lines accounts.

For 2025, our full-year expectations are as follows:

•A GAAP combined ratio of 96% to 97%, including net catastrophe losses of 6 points. Our combined ratio estimate assumes no prior year casualty reserve development;

•After-tax net investment income of $405 million;

•An overall effective tax rate of 21.5%; and

•Weighted average shares of 61.5 million on a fully diluted basis.

Results of Operations and Related Information by Segment

Insurance Operations

The following table provides quantitative information for analyzing the combined ratio:

Insurance Operations Results:

Less:

Combined Ratios:

Dividends to policyholders ratio 0.1 0.2 (0.1) 0.1 0.1

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The NPW growth of 12% in 2024 compared to 2023 included:

Renewal pure price increases 9.5 % 6.8 5.1

Our NPW growth in 2024 also benefited from (i) exposure growth on renewal policies and (ii) stable retention in our Standard Commercial Lines and E&S Lines.

The increase in NPE in 2024 compared to 2023 resulted from the same impacts to NPW described above.

Loss and Loss Expenses

The following table provides quantitative information for analyzing loss and loss expense incurred:

Loss and Loss Expense Incurred:

Impact on Loss and Loss Expense Ratio:

Non-catastrophe property loss and loss expenses 15.6 17.0 (1.4) 18.3 (1.3)

Prior Year Casualty Reserve Development and Current Year Casualty Loss Costs

The loss and loss expense ratio increased 7.4 points in 2024 compared to 2023, primarily driven by:

•An increase of 7.3 points in unfavorable prior year casualty reserve development in 2024 compared to 2023. In 2024, we recorded $311 million of unfavorable prior year casualty reserve development compared to $6.5 million, or 0.2 points, of favorable prior year casualty reserve development in 2023. Our 2024 calendar year actions were predominantly in the general liability line for accident years 2020 and subsequent, with most of the actions for accident years 2022 and 2023; and

•An increase of 1.4 points in current year casualty loss costs in 2024 compared to 2023, primarily due to increased loss trend expectations and higher prior-year severity assumptions related to the impacts of social inflation on our general liability and E&S casualty lines of business.

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Details of the prior year casualty reserve development by reportable segment and line of business were as follows:

(Favorable)/Unfavorable Prior Year Casualty Reserve Development

Businessowners' policies — — (11.0)

Total Standard Commercial Lines 286.0 (15.5) (81.0)

Homeowners (5.0) — —

Personal automobile 10.0 14.0 —

Total Standard Personal Lines 5.0 14.0 —

The 2024 unfavorable prior year casualty reserve development by line of business was driven by the following:

•General liability - increased severities in accident years 2020 and subsequent, with most of the actions for accident years 2022 and 2023, due to impacts from social inflation;

•Commercial automobile - increased severities in accident year 2023;

•Personal automobile - increased severities in accident years 2022 through 2023; and

•E&S casualty - increased severities in accident years 2023 and prior.

Favorable prior year casualty reserve development on our workers' compensation, bonds, and homeowners lines of business provided a partial offset to the items above. The favorable prior year casualty reserve development on the workers compensation line was primarily driven by improved severities in accident years 2022 and prior.

The 2023 favorable prior year casualty reserve development was primarily driven by favorable development on our workers compensation line of business, due to improved loss severities driven by continued favorable medical cost trends in accident years 2021 and prior. Partially offsetting this favorable development was unfavorable development on our general liability and personal automobile lines of business. The unfavorable prior year development on (i) general liability was primarily driven by increased loss severities in accident years 2015 through 2020 attributable to social inflation and (ii) personal automobile was primarily driven by increased loss severities in accident year 2022.

For additional qualitative discussion on prior year casualty reserve development and current year casualty loss costs, refer to the insurance segment sections below.

Property Losses

Net catastrophe and non-catastrophe property losses reduced the loss and loss expense ratio by 1.3 points in the aggregate in 2024 compared to 2023. The non-catastrophe property loss and loss expense ratio was 1.4 points lower in 2024 compared to 2023, reflecting (i) the earned impact of higher renewal pure price increases in 2024, (ii) lower claim frequencies, and (iii) variability from period to period of non-catastrophe weather. Net catastrophe losses were in line with last year, with the single largest event being Hurricane Helene for $85.0 million, or 1.9 points. Hurricane Helene occurred in late September 2024 and primarily impacted states in our Southeastern footprint.

For additional qualitative discussion on non-catastrophe property loss and loss expenses, refer to the insurance segment sections below.

Underwriting Expenses

The underwriting expense ratio was 0.8 points lower in 2024 compared to 2023, primarily due to lower expected profit-based employee compensation and growth in premium outpacing growth in underwriting expenses.

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Standard Commercial Lines Segment

Insurance Segments Results:

Less:

Combined Ratios:

Dividends to policyholders ratio 0.2 0.2 — 0.2 —

NPW growth of 11% in 2024 compared to 2023 included:

For the Year Ended December 31,

Direct new business premiums $ 619.1 $ 597.5

Renewal pure price increases on NPW 8.3 7.0

In addition, NPW growth in 2024 benefited from strong exposure growth on renewal policies.

The increase in NPE in 2024 compared to 2023 resulted from the same impacts to NPW described above.

Loss and Loss Expenses

The following table provides quantitative information for analyzing loss and loss expense incurred:

Loss and Loss Expense Incurred:

Non-catastrophe property loss and loss expenses 459,537 461,593 —

Impact on Loss and Loss Expense Ratio:

Current year casualty loss costs 45.6 43.1 2.5

Net catastrophe losses 5.3 4.9 0.4

Non-catastrophe property loss and loss expenses 13.3 15.0 (1.7)

Total loss and loss expense incurred 72.5 62.5 10.0

Prior Year Casualty Reserve Development and Current Year Casualty Loss Costs

The loss and loss expense ratio increased 10.0 points in 2024 compared to 2023, primarily driven by:

•An increase of 8.8 points in unfavorable prior year casualty reserve development in 2024 compared to 2023. In 2024, we recorded $286.0 million of unfavorable prior year casualty reserve development compared to $15.5 million, or 0.5 points, of favorable prior year casualty reserve development in 2023. Our 2024 calendar year actions were predominantly in the general liability line for accident years 2020 and subsequent, with most of the actions for accident years 2022 and 2023; and

•An increase of 2.5 points in current year casualty loss costs in 2024 compared to 2023, primarily due to increased loss trend expectations and higher prior-year severity assumptions related to the impacts of social inflation on our general liability line.

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Details of the prior year casualty reserve development by line of business were as follows:

(Favorable)/Unfavorable Prior Year Casualty Reserve Development

Businessowners' policies — — (11.0)

Total Standard Commercial Lines 286.0 (15.5) (81.0)

Refer to the line of business sections below for qualitative discussion on the significant drivers of unfavorable prior year casualty reserve development and current year casualty loss costs.

Property Losses

Net catastrophe and non-catastrophe property losses reduced the loss and loss expense ratio by 1.3 points in the aggregate in 2024 compared to 2023. The non-catastrophe property loss and loss expense ratio was 1.7 points lower in 2024 compared to 2023, reflecting (i) the earned impact of higher renewal pure price increases in 2024, (ii) lower claim frequencies, and (iii) variability from period to period of non-catastrophe weather. Net catastrophe losses were 0.4 points higher than last year, driven by Hurricane Helene, our single largest event in 2024, resulting in $65.5 million, or 1.9 points.

Refer to the line of business sections below for qualitative discussion on the significant drivers of non-catastrophe property loss and loss expenses.

Underwriting Expenses

The underwriting expense ratio was 0.7 points lower in 2024 compared to 2023, primarily due to lower expected profit-based employee compensation and growth in premium outpacing growth in underwriting expenses.

The following is a discussion of our most significant Standard Commercial Lines of business:

General Liability

Renewal pure price increases 8.6 5.4 n/a 4.5 n/a

% of total Standard Commercial Lines NPW 33 33 33

1n/a: not applicable.

NPW grew 9% in 2024 compared to 2023, benefiting from renewal pure price increases, exposure growth on renewal policies, and strong retention.

The combined ratio was 33.2 points higher in 2024 compared to 2023, primarily driven by the following:

Loss and Loss Expense Incurred:

Impact on Loss and Loss Expense Ratio:

Current year casualty loss costs 67.0 56.0 11.0

Total loss and loss expense incurred 95.1 61.4 33.7

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The general liability line of business has experienced a long-term historical trend of meaningful severity increases that have been partially offset by claim frequency decreases. Prior-year severities have developed adversely. Although we saw these trends primarily impact the pre-pandemic period in 2023, we have seen elevated severity escalation extend into the more recent accident years during 2024. We attribute the increased severities to elevated social inflation, which we view as an industry dynamic characterized by higher claimant propensity for attorney representation and litigation, longer settlement times, and higher settlement values. We are closely monitoring specific jurisdictions with expanded liability definitions and interpretations and higher damage awards for loss trend impact and broader industry trends.

Although we planned for higher expected loss trends, claim emergence in 2024 exceeded our expectations. In response to these unfavorable trends due to the impact of social inflation, we recorded unfavorable prior year casualty reserve development of $316.0 million in 2024 for accident years 2020 and subsequent, with most actions for accident years 2022 and 2023. Additionally, current year casualty loss costs were 11.0 points higher in 2024 compared to 2023, primarily due to increased loss trend expectations and higher prior-year severity assumptions. If severities continue to emerge higher than expected, this line's ultimate loss estimates could be adversely impacted.

We believe that social inflation and elevated loss trends are an industry dynamic, which may lead to an acceleration of rate increases in this line of business for the industry and us. Given the consistency in our underwriting appetite and risk profile over time, we have focused our actions primarily on prudent underwriting and achieving additional rate. Our renewal pure price increase in this line of business accelerated to 8.6% in 2024, up from 5.4% in 2023.

Despite the adverse emergence in general liability, we remain comfortable with the composition and quality of our underwriting portfolio. While rate increases will continue to be the primary focus for profitability improvement, we are also making underwriting refinements, including managing limits and coverage grants in challenging jurisdictions, driving improved terms and conditions, and focusing production on better-performing classes of business.

Commercial Automobile

Renewal pure price increases 10.7 9.8 n/a 8.1 n/a

% of total Standard Commercial Lines NPW 31 30 30

1n/a: not applicable.

NPW grew 15% in 2024 compared to 2023, benefiting from renewal pure price increases, strong retention, and higher direct new business. This strong retention and higher direct new business contributed to a 5% growth of in-force vehicle counts as of December 31, 2024, compared to December 31, 2023.

The combined ratio was 3.9 points lower in 2024 compared to 2023, primarily driven by the following:

Loss and Loss Expense Incurred:

Non-catastrophe property loss and loss expenses 172,094 177,803 (3)

Impact on Loss and Loss Expense Ratio:

Current year casualty loss costs 51.5 53.5 (2.0)

Net catastrophe losses 0.8 0.5 0.3

Non-catastrophe property loss and loss expenses 16.3 19.4 (3.1)

Total loss and loss expense incurred 70.5 73.8 (3.3)

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Non-catastrophe property loss and loss expenses in 2024 were lower compared to 2023, primarily due to (i) the earned impact of higher renewal pure price increases in 2024 and (ii) lower claim frequencies. In addition, the current year casualty loss costs ratio was 2.0 points lower in 2024 compared to 2023, primarily driven by the earned impact of higher renewal pure price increases in 2024.

Partially offsetting the favorable combined ratio drivers mentioned above, was unfavorable prior year casualty reserve development in 2024, primarily due to increased severities in accident year 2023. The 2023 unfavorable prior year casualty reserve development was primarily due to increased loss expenses in accident years 2022 and prior.

Commercial Property1

Renewal pure price increases 10.0 9.8 n/a 6.2 n/a

% of total Standard Commercial Lines NPW 20 20 18

1includes Inland Marine.

2n/a: not applicable.

NPW grew 14% in 2024 compared to 2023 benefiting from renewal pure price increases, strong retention, and exposure growth on renewal policies.

The combined ratio was 6.0 points lower in 2024 compared to 2023, primarily driven by the following:

Non-catastrophe property loss and loss expense ratios were lower in 2024 compared to 2023, reflecting (i) the earned impact of higher renewal pure price increases in 2024 and (ii) the continued variability from period to period normally associated with the commercial property line of business. We continue to manage our long-term profitability through (i) price increases and (ii) targeted underwriting actions, including an ongoing focus on appropriate policy terms and conditions and achieving accurate insurance-to-value ratios, in part, by using automated aerial imagery solutions.

In addition, the underwriting expense ratio was 1.4 points lower in 2024 compared to 2023, as discussed in the "Standard Commercial Lines Segment" section above.

Workers Compensation

Renewal pure price increases (decreases) (2.8) (1.5) n/a (0.5) n/a

% of total Standard Commercial Lines NPW 9 12 12

1n/a: not applicable.

NPW decreased 5% in 2024 compared to 2023, primarily due to renewal pure price decreases and a reduction in direct new business.

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The combined ratio was 11.0 points higher in 2024 compared to 2023, primarily due to the following:

The favorable prior year casualty reserve development in 2024 was primarily due to improved loss severities in accident years 2022 and prior. The favorable prior year casualty reserve development in 2023 was primarily due to improved loss severities driven by continued favorable medical cost trends in accident years 2021 and prior.

In addition, the combined ratio was adversely impacted by an increase in current year casualty loss costs of 3.2 points in 2024, primarily driven by loss trend outpacing rate level reductions associated with workers compensation rating bureau loss cost reductions.

Standard Personal Lines Segment

Insurance Segments Results:

Less:

Combined Ratios:

NPW increased 4% in 2024 compared to 2023, primarily due to renewal pure price increases, exposure growth on renewal policies, and higher average policy sizes from our mass affluent market strategy, partially offset by reductions in direct new business and retention. The reduction in direct new business premiums was primarily due to a decrease in new policy counts, which were down 51% in 2024 compared to 2023. These reductions, and the reduction in retention illustrated in the table below, resulted from the rate increases we are implementing as part of our overall profit improvement plan.

Direct new business premiums1 $ 72.6 $ 116.5

Renewal pure price increases on NPW 20.6 5.2

1Excludes our flood direct premiums written, which is 100% ceded to the NFIP and therefore, has no impact on our NPW.

In recent years, we've been taking aggressive actions to improve the profitability of this business by prioritizing additional rate filings to attain premiums in line with current loss costs, and further refining our pricing factors. These filed rate increases began to take effect early in 2023 and increased in number and magnitude throughout 2023 and 2024. In 2025, we expect rate changes to remain above loss trends but will moderate compared to the filed rate increases in 2023 and 2024. Renewal pure prices increased 20.6% in 2024, a direct outcome of these actions. In addition, we are continuing to seek improved profitability within our homeowners line of business by expanding the use of new policy terms and conditions, including (i) coverage for older roofs based on a schedule of factors rather than replacement cost and (ii) implementing mandatory wind/hail deductibles in states exposed to severe convective storms, where allowed by law.

The increase in NPE in 2024 compared to 2023 resulted from the same impacts on NPW discussed above.

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Loss and Loss Expenses

The following table provides quantitative information for analyzing loss and loss expense incurred:

Loss and Loss Expense Incurred:

Impact on Loss and Loss Expense Ratio:

Current year casualty loss costs 27.2 30.9 (3.7)

Non-catastrophe property loss and loss expenses 38.6 43.0 (4.4)

Total loss and loss expense incurred 85.8 96.7 (10.9)

Prior Year Casualty Reserve Development and Current Year Casualty Loss Costs

The loss and loss expense ratio decreased 10.9 points in 2024 compared to 2023, primarily driven by (i) a decrease of 2.6 points in unfavorable prior year casualty reserve development in 2024 compared to 2023 and (ii) a decrease of 3.7 points in current year casualty loss costs in 2024 compared to 2023. The decrease in current year casualty loss costs in 2024 compared to 2023 was primarily due to (i) significant rate increases, and (ii) a 1.0-point increase in flood claims handling fees related to Hurricane Helene from our participation in the NFIP.

Details of the prior year casualty reserve development by line of business were as follows:

(Favorable)/Unfavorable Prior Year Casualty Reserve Development

Homeowners $ (5.0) —

Total Standard Personal Lines 5.0 14.0

Prior year casualty reserve development in 2024 included $10.0 million of unfavorable development in personal automobile, primarily driven by increased loss severities in accident years 2022 through 2023. This was partially offset by $5.0 million of favorable development in homeowners, primarily due to lower loss severities in accident years 2021 and prior.

The unfavorable prior year casualty reserve development in 2023 was primarily attributable to increased loss severities in accident year 2022 on our personal automobile line of business.

Property Losses

Net catastrophe and non-catastrophe property losses reduced the loss and loss expense ratio by 4.6 points in the aggregate in 2024 compared to 2023. Non-catastrophe property loss and loss expense ratios were lower in 2024 compared to 2023 due to (i) the earned impact of higher renewal pure price increases in 2024 and (ii) variability from period to period of non-catastrophe weather. Net catastrophe losses were in line with last year and included $17.4 million, or 4.1 points, related to Hurricane Helene.

Underwriting Expenses

The underwriting expense ratio was 1.5 points lower in 2024 compared to 2023, primarily due to lower profit-based employee compensation and growth in premiums earned outpacing growth in underwriting expenses.

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E&S Lines Segment

Insurance Segments Results:

Less:

Combined Ratios:

NPW growth of 29% in 2024 compared to 2023 included:

Direct new business premiums $ 302.6 209.5

Renewal pure price increases on NPW 7.2 % 6.9

In addition, NPW growth in 2024 benefited from both property and casualty exposure growth on renewal policies and higher rates per exposure.

The increase in NPE in 2024 compared to 2023 resulted from the same impacts to NPW discussed above.

Loss and Loss Expenses

The following table provides quantitative information for analyzing loss and loss expense incurred:

Loss and Loss Expense Incurred:

SIGI US Equity

SIGI · 10-K · period ended 2024-12-31

Item 1A. Risk Factors.

Item 1B. Unresolved Staff Comments.

Item 1C. Cybersecurity.

Item 2. Properties.

Item 3. Legal Proceedings.

Item 4. Mine Safety Disclosures.

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

Item 6. Reserved.

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

SIGI US Equity☆

SIGI · 10-K · period ended 2024-12-31

Item 1A. Risk Factors.

Item 1B. Unresolved Staff Comments.

Item 1C. Cybersecurity.

Item 2. Properties.

Item 3. Legal Proceedings.

Item 4. Mine Safety Disclosures.

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

Item 6. Reserved.

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

SIGI US Equity