Merck & Co. Inc.: 10-K Risk Factor Changes

The Company believes that climate change has the potential to negatively affect its business, results of operations, cash flows and prospects. The Company is exposed to physical risks (such as extreme weather conditions, inland flooding or rising sea levels), risks in transitioning to a low-carbon economy (such as additional legal or regulatory requirements, changes in technology, market risk and reputational risk) and social and human effects (such as population dislocations and harm to health and well-being) associated with climate change. These risks can be either acute (short-term) or chronic (long-term). The adverse impacts of climate change include increased frequency and severity of natural disasters and extreme weather events such as hurricanes, tornados, wildfires (exacerbated by drought), flooding, and extreme heat. Extreme weather, inland flooding and sea-level rise pose physical risks to the Company’s facilities as well as those of its suppliers. Such risks include losses incurred as a result of physical damage to facilities, loss or spoilage of inventory, and business interruption caused by such natural disasters and extreme weather events. Other potential physical impacts due to climate change include reduced access to high-quality water in certain regions and the loss of biodiversity, which could impact future product development. These risks could disrupt the Company’s operations and its supply chain, which may result in increased costs. New legal and regulatory requirements with respect to climate-related matters, which may differ across jurisdictions, could result in the Company being subject to increased compliance burdens and costs to meet these obligations. The Company’s supply chain would likely be subject to similar risks and would likely pass along any increased costs to the Company, which may affect the Company’s ability to procure raw materials or other supplies required for the operation of the Company’s business at the quantities and levels required.

The Company believes that climate change has the potential to negatively affect its business, results of operations, cash flows and prospects. The Company is exposed to physical risks (such as extreme weather conditions, inland flooding or rising sea levels), risks in transitioning to a low-carbon economy (such as additional legal or regulatory requirements, changes in technology, market risk and reputational risk) and social and human effects (such as population dislocations and harm to health and well-being) associated with climate change. These risks can be either acute (short-term) or chronic (long-term). The adverse impacts of climate change include increased frequency and severity of natural disasters and extreme weather events such as hurricanes, tornados, wildfires (exacerbated by drought), flooding, and extreme heat. Extreme weather, inland flooding and sea-level rise pose physical risks to the Company’s facilities as well as those of its suppliers. Such risks include losses incurred as a result of physical damage to facilities, loss or spoilage of inventory, and business interruption caused by such natural disasters and extreme weather events. Other potential physical impacts due to climate change include reduced access to high-quality water in certain regions and the loss of biodiversity, which could impact future product development. These risks could disrupt the Company’s operations and its supply chain, which may result in increased costs. New legal and regulatory requirements are being enacted to prevent, mitigate, or adapt to the implications of a changing climate and its effects on the environment. These regulations, which may differ across jurisdictions, could result in the Company being subject to new or expanded carbon pricing or taxes, increased compliance costs, restrictions on GHG emissions, investment in new technologies, increased GHG emission disclosure (including costs resulting from mandatory or voluntary reporting, diligence or disclosure) and transparency, recurring investments in data gathering and reporting systems, upgrades of facilities to meet new building codes, and the redesign of utility systems, which could increase the Company’s operating costs, including the cost of electricity and energy used by the Company. The Company’s supply chain would likely be subject to these same transitional risks and would likely pass along any increased costs to the Company, which may affect the Company’s ability to procure raw materials or other supplies required for the operation of the Company’s business at the quantities and levels required.

Governmental authorities, non-governmental organizations, customers, investors, external stakeholders and employees are sensitive to environmental, social and governance concerns, such as human capital, climate change, water use, recyclability or recoverability of packaging, and plastic waste. The focus on these concerns may lead to new requirements that could result in increased costs associated with developing, manufacturing and distributing the Company’s products, and related reporting obligations. The Company’s ability to compete could also be affected by changing customer preferences and requirements, such as growing demand for validated net zero GHG emission targets and more environmentally friendly products, packaging or supplier practices, or by failure to meet such customer expectations or demand. The Company risks negative shareholder reaction, including from proxy advisory services, as well as damage to its brand and reputation and inability to attract and retain employee talent, if the Company fails to act responsibly, or if the Company is perceived to not be acting responsibly, in key areas, including equitable access to medicines and vaccines, product quality and safety, environmental stewardship, reduction of GHG emissions, support for local communities, corporate governance and transparency, and addressing human capital factors in the Company’s operations. Responding to these considerations as well as any applicable regulatory requirements and implementation of the Company’s goals and initiatives involves risks and uncertainties, requires investments, and depends in part on third-party performance or data that is outside of the Company’s control. In addition, some governmental authorities, non-governmental organizations, and stakeholders may disagree with the Company’s goals and initiatives. If the Company does not meet the rapidly evolving and varied regulatory requirements and expectations of its investors, customers and other stakeholders, the Company could experience negative impacts to the Company’s business and results of operations. In addition, the Company is subject to evolving mandatory and voluntary reporting, diligence and disclosure requirements, including the EU’s Corporate Sustainability Reporting Directive (CSRD) and potentially the SEC’s climate-related reporting requirements (which are currently stayed), the legislation in California requiring reporting of GHG emissions (which is currently subject to legal challenge) and climate risk (which is currently stayed pending appeal), and similar regulatory requirements in other jurisdictions outside the U.S. These evolving regulatory requirements may result in increased costs and complexities of compliance in order to collect, measure and report on the relevant information, and could expose the Company to the risk of government enforcement actions and private litigation. 33 33 33 33 33 33 Table of Contents Table of Contents Table of Contents

Governmental authorities, non-governmental organizations, customers, investors, external stakeholders and employees are sensitive to environmental, social and governance concerns, such as human capital, climate change, water use, recyclability or recoverability of packaging, and plastic waste. The focus on these concerns may lead to new requirements that could result in increased costs associated with developing, manufacturing and distributing the Company’s products, and related reporting obligations. The Company’s ability to compete could also be affected by changing customer preferences and requirements, such as growing demand for validated net zero GHG emission targets and more environmentally friendly products, packaging or supplier practices, or by failure to meet such customer expectations or demand. The Company risks negative shareholder reaction, including from proxy advisory services, as well as damage to its brand and reputation and inability to attract and retain employee talent, if the Company fails to act responsibly, or if the Company is perceived to not be acting responsibly, in key areas, including equitable access to medicines and vaccines, product quality and safety, environmental stewardship, reduction of GHG emissions, support for local communities, corporate governance and transparency, and addressing human capital factors in the Company’s operations. Responding to these considerations as well as any applicable regulatory requirements and implementation of the Company’s goals and initiatives involves risks and uncertainties, requires investments, and depends in part on third-party performance or data that is outside of the Company’s control. In addition, some governmental authorities, non-governmental organizations, and stakeholders may disagree with the Company’s goals and initiatives. If the Company does not meet the evolving and varied regulatory requirements and expectations of its investors, customers and other stakeholders, the Company could experience negative impacts to the Company’s business and results of operations. In addition, the Company is subject to expanding mandatory and voluntary reporting, diligence and disclosure requirements, including the EU’s Corporate 32 32 32 32 32 32 Table of Contents Table of Contents Table of Contents Sustainability Reporting Directive (CSRD) and potentially the SEC’s climate-related reporting requirements (which are currently stayed), the legislation in California requiring reporting of GHG emissions and climate risk, and similar regulatory requirements in other jurisdictions outside the U.S. These evolving regulatory requirements are likely to result in increased costs and complexities of compliance in order to collect, measure and report on the relevant information.

The Company’s ability to generate profits and operating cash flows depends largely upon the continued profitability of the Company’s key products, such as Keytruda, Gardasil/Gardasil 9, Lynparza, Winrevair, and Bravecto. In particular, in the aggregate, in 2025, sales of Keytruda represented 49% of the Company’s total sales. As a result of the Company’s dependence on key products, any event that adversely affects any of these products or the markets for any of these products, such as the materially lower demand for Gardasil/Gardasil 9 in China which the Company has experienced, could have a significant adverse impact on results of operations, cash flows, financial condition, and prospects. Other events could include loss of patent protection, selection for IRA price setting, lower than expected utilization of Keytruda Qlex, increased costs associated with manufacturing, generic, biosimilar or over-the-counter availability of the Company’s product or a competitive product, the discovery of previously unknown side effects, results of post-approval trials, increased competition from the introduction of new, more effective treatments and discontinuation or removal from the market of the product for any reason. Such events could have a material adverse effect on the sales of any such products.

The Company’s ability to generate profits and operating cash flows depends largely upon the continued profitability of the Company’s key products, such as Keytruda, Gardasil/Gardasil 9, Lynparza, Bravecto, and Bridion. In 2024, the Company’s oncology portfolio, led by Keytruda, represented substantially all of the Company’s revenue growth. In particular, in the aggregate, in 2024, sales of Keytruda represented 46% of the Company’s total sales. As a result of the Company’s dependence on key products, any event that adversely affects any of these products or the markets for any of these products, such as the slowing demand for Gardasil/Gardasil 9 in China which the Company has experienced, could have a significant adverse impact on results of operations and financial condition. Other events could include loss of patent protection, increased costs associated with manufacturing, generic or over-the-counter availability of the Company’s product or a competitive product, the discovery of previously unknown side effects, results of post-approval trials, increased competition from the introduction of new, more effective treatments and discontinuation or removal from the market of the product for any reason. Such events could have a material adverse effect on the sales of any such products.

Product candidates or uses that appear promising in development may fail to reach the market or fail to succeed for numerous reasons, including the following: •findings of ineffectiveness, superior safety or efficacy of competing products, or harmful side effects in clinical or preclinical testing; •failure to receive the necessary regulatory approvals, including delays in the approval of new products and new indications, or the anticipated labeling, and uncertainties about the time required to obtain regulatory approvals and the benefit/risk standards applied by regulatory agencies in determining whether to grant approvals; •failure in certain markets to obtain reimbursement commensurate with the level of innovation and clinical benefit presented by the product; •changes in clinical preferences or standards of care, including competitor innovations, that diminish the value of the product; •lack of economic feasibility due to manufacturing costs or other factors; and •preclusion from commercialization by the proprietary rights of others. In the future, if certain pipeline programs are cancelled or if the Company believes that their commercial prospects have been reduced, the Company may recognize material non-cash impairment charges for those programs that were measured at fair value and capitalized in connection with acquisitions or certain collaborations. Failure to successfully develop and market new products in the short term or long term would have a material adverse effect on the Company’s business, results of operations, cash flows, financial condition and prospects.

Products that appear promising in development may fail to reach the market or fail to succeed for numerous reasons, including the following: •findings of ineffectiveness, superior safety or efficacy of competing products, or harmful side effects in clinical or preclinical testing; 29 29 29 29 29 29 Table of Contents Table of Contents Table of Contents •failure to receive the necessary regulatory approvals, including delays in the approval of new products and new indications, or the anticipated labeling, and uncertainties about the time required to obtain regulatory approvals and the benefit/risk standards applied by regulatory agencies in determining whether to grant approvals; •failure in certain markets to obtain reimbursement commensurate with the level of innovation and clinical benefit presented by the product; •lack of economic feasibility due to manufacturing costs or other factors; and •preclusion from commercialization by the proprietary rights of others. In the future, if certain pipeline programs are cancelled or if the Company believes that their commercial prospects have been reduced, the Company may recognize material non-cash impairment charges for those programs that were measured at fair value and capitalized in connection with acquisitions or certain collaborations. Failure to successfully develop and market new products in the short term or long term would have a material adverse effect on the Company’s business, results of operations, cash flows, financial condition and prospects.

The Company’s activities, including research, preclinical testing, clinical trials and the manufacturing and marketing of its products, are subject to extensive regulation by numerous federal, state and local governmental authorities in the U.S., including the FDA, and by foreign regulatory authorities, including in the EU, Japan and China. In the U.S., the FDA administers requirements covering the testing, approval, safety, effectiveness, manufacturing, labeling and marketing of prescription pharmaceuticals and vaccines. In some cases, the FDA requirements have increased the amount of time and resources necessary to develop new products and bring them to market in the U.S. Regulation outside the U.S. also is primarily focused on drug safety and effectiveness and, in many cases, reduction in the cost of drugs. The FDA and foreign regulatory authorities, including in the EU, Japan and China, have substantial discretion to require additional testing, to delay or withhold registration and marketing approval and to otherwise preclude distribution and sale of a product. Even if the Company is successful in developing new products, it will not be able to market any of those products unless and until it has obtained all required regulatory approvals (which in limited circumstances may include authorizations for emergency use) in each jurisdiction where it proposes to market the new products. Once obtained, the Company must maintain approval as long as it plans to market its new products in each jurisdiction where approval is required. The Company’s failure to obtain approval, significant delays in the approval process, or its 37 37 37 37 37 37 Table of Contents Table of Contents Table of Contents failure to maintain approval in any jurisdiction will prevent it from selling the products in that jurisdiction and realizing sales.

The Company’s activities, including research, preclinical testing, clinical trials and the manufacturing and marketing of its products, are subject to extensive regulation by numerous federal, state and local governmental authorities in the U.S., including the FDA, and by foreign regulatory authorities, including in the EU, Japan and China. In the U.S., the FDA administers requirements covering the testing, approval, safety, effectiveness, manufacturing, labeling and marketing of prescription pharmaceuticals and vaccines. In some cases, the FDA requirements have increased the amount of time and resources necessary to develop new products and bring them to market in the U.S. Regulation outside the U.S. also is primarily focused on drug safety and effectiveness and, in many cases, reduction in the cost of drugs. The FDA and foreign regulatory authorities, including in the EU, Japan and China, have substantial discretion to require additional testing, to delay or withhold registration and marketing approval and to otherwise preclude distribution and sale of a product. 36 36 36 36 36 36 Table of Contents Table of Contents Table of Contents Even if the Company is successful in developing new products, it will not be able to market any of those products unless and until it has obtained all required regulatory approvals (which in limited circumstances may include authorizations for emergency use) in each jurisdiction where it proposes to market the new products. Once obtained, the Company must maintain approval as long as it plans to market its new products in each jurisdiction where approval is required. The Company’s failure to obtain approval, significant delays in the approval process, or its failure to maintain approval in any jurisdiction will prevent it from selling the products in that jurisdiction and realizing sales.

The Company depends on third parties, including suppliers, distributors, alliances with other pharmaceutical and biotechnology companies, and third-party service providers, for key aspects of its business including development, manufacture and commercialization of its products and support for its information technology (IT) systems. Failure of these third parties to meet their contractual, regulatory and other obligations to the Company or the development of factors that materially disrupt the relationships between the Company and these third parties could have a material adverse effect on the Company’s business.

The Company depends on third parties, including suppliers, distributors, alliances with other pharmaceutical and biotechnology companies, and third-party service providers, for key aspects of its business including development, manufacture and commercialization of its products and support for its information technology (IT) systems. Failure of these third parties to meet their contractual, regulatory and other obligations to the Company or the development of factors that materially disrupt the relationships between the Company and these third parties could have a material adverse effect on the Company’s business. 34 34 34 34 34 34 Table of Contents Table of Contents Table of Contents

The inappropriate and/or unauthorized use of certain social media and mobile messaging channels could cause brand damage or information leakage or could lead to legal implications, including from the improper collection and/or dissemination of personally identifiable information. In addition, negative or inaccurate posts or comments about the Company or its products on any social networking platforms could damage the Company’s reputation, brand image and goodwill. Further, the disclosure of non-public Company-sensitive information by the Company’s workforce or others through external media channels could lead to information loss. Although there are internal Company Social Media and Mobile Messaging Policies that guide employees on appropriate personal and professional use of these platforms for communication about the Company, the processes in place may not completely secure and protect information. Identifying potential new points of unauthorized entry as new communication tools expand also presents new challenges. 40 40 40 40 40 40 Table of Contents Table of Contents Table of Contents

The inappropriate and/or unauthorized use of certain social media and mobile messaging channels could cause brand damage or information leakage or could lead to legal implications, including from the improper collection and/or dissemination of personally identifiable information. In addition, negative or inaccurate posts or comments about the Company or its products on any social networking platforms could damage the Company’s reputation, brand image and goodwill. Further, the disclosure of non-public Company-sensitive information by the Company’s workforce or others through external media channels could lead to information loss. Although there are internal Company Social Media and Mobile Messaging Policies that guide employees on appropriate personal and professional use of these platforms for communication about the Company, the processes in place may not completely secure and protect information. Identifying potential new points of unauthorized entry as new communication tools expand also presents new challenges. 39 39 39 39 39 39 Table of Contents Table of Contents Table of Contents

As a result of a number of factors, product liability insurance has become less available while the cost of such insurance has increased significantly. The Company is subject to a substantial number of product liability claims. See Item 8. “Financial Statements and Supplementary Data,” Note 10. “Contingencies and Environmental Liabilities” below for more information on the Company’s current product liability litigation. With respect to product liability, the Company self-insures substantially all of its risk, as the availability of commercial insurance has become more restrictive. The Company has evaluated its risks and has determined that the cost of obtaining product liability insurance outweighs the likely benefits of the coverage that is available and, as such, has no insurance for most product liabilities. The Company will continually assess the most efficient means to address its risk; however, there can be no guarantee that insurance coverage will be obtained or, if obtained, will be sufficient to fully cover product liabilities that may arise. 39 39 39 39 39 39 Table of Contents Table of Contents Table of Contents

As a result of a number of factors, product liability insurance has become less available while the cost of such insurance has increased significantly. The Company is subject to a substantial number of product liability claims. See Item 8. “Financial Statements and Supplementary Data,” Note 10. “Contingencies and Environmental Liabilities” below for more information on the Company’s current product liability litigation. With respect to product liability, the Company self-insures substantially all of its risk, as the availability of commercial insurance has become more restrictive. The Company has evaluated its risks and has determined that the cost of obtaining product liability insurance outweighs the likely benefits of the coverage that is available and, as such, has no insurance for most product liabilities. The Company will continually assess the most efficient means to address its risk; however, there can be no guarantee that insurance coverage will be obtained or, if obtained, will be sufficient to fully cover product liabilities that may arise. 38 38 38 38 38 38 Table of Contents Table of Contents Table of Contents

The Company faces continued pricing pressure globally and, particularly in mature markets, from managed care organizations, government agencies and programs that could negatively affect the Company’s sales 30 30 30 30 30 30 Table of Contents Table of Contents Table of Contents and profit margins. In the U.S., these include (i) U.S. federal laws and regulations related to Medicare and Medicaid, including the Medicare Prescription Drug Improvement and Modernization Act of 2003, the ACA, and the IRA, (ii) practices of managed care groups and institutional and governmental purchasers, and (iii) state activities aimed at increasing price transparency, including new laws as noted above in Item 1. “Competition and the Health Care Environment.” Changes to the health care system enacted as part of health care reform in the U.S., as well as increased purchasing power of entities that negotiate on behalf of Medicare, Medicaid, and private sector beneficiaries, could result in further pricing pressures. As noted in Item 1. “Competition and the Health Care Environment,” in 2023, HHS selected Januvia for the first year of the IRA’s price setting program, which resulted in a government set price becoming effective on January 1, 2026. In 2025, HHS selected Janumet and Janumet XR for government price setting, which will become effective on January 1, 2027. In addition, in January 2026, HHS announced that Lenvima has been selected for government price setting, the set price for which will become effective on January 1, 2028. Furthermore, the Company expects that in 2027 HHS will include Keytruda in a subsequent selection of products to undergo IRA price setting, with such price to become effective on January 1, 2029 and the Company expects that, as a result, U.S. sales of Keytruda will decline materially after that time. Government price setting may also impact pricing in the private market, negatively affecting the Company’s performance. Also, as noted above, in December 2025, the Company entered into the MFN Agreement with the U.S. government pursuant to which the Company will provide key products through a direct-to-patient program at affordable prices for eligible patients in the U.S. This currently includes Januvia, Janumet, and Janumet XR, and will be expanded in the future to include enlicitide decanoate pending FDA approval. The Company also agreed to offer its existing medicines at discounted prices to Medicaid, excluding certain products. In addition, the Company has agreed that products launched during the term of the MFN Agreement (with certain exceptions) will be subject to “most-favored-nation” pricing in reference to prices for such products in the MFN Countries. In addition, in the U.S., larger customers have received higher rebates on drugs in certain highly competitive categories. The Company must also compete to be placed on formularies of managed care organizations. Exclusion of a product from a formulary can lead to reduced usage in the managed care organization. The Company is also facing pricing pressure from purchasers of certain vaccines in highly competitive categories. Also, the Company expects that U.S. states will continue their focus on pharmaceutical pricing and may shift to more aggressive price control tools. Outside the U.S., numerous major markets, including the EU, Japan and China have pervasive government involvement in funding health care and, in that regard, fix the pricing and reimbursement of pharmaceutical and vaccine products. Consequently, in those markets, the Company is subject to government decision making and budgetary actions with respect to its products. In Japan, the pharmaceutical industry is subject to government-mandated annual price reductions of pharmaceutical products and certain vaccines. Furthermore, the Japanese government can order re-pricing for specific products if it determines that use of such product will exceed certain thresholds defined under applicable re-pricing rules. The Company expects pricing pressures to continue in the future.

The Company faces continued pricing pressure globally and, particularly in mature markets, from managed care organizations, government agencies and programs that could negatively affect the Company’s sales and profit margins. In the U.S., these include (i) U.S. federal laws and regulations related to Medicare and Medicaid, including the Medicare Prescription Drug Improvement and Modernization Act of 2003, the ACA, and the IRA, (ii) practices of managed care groups and institutional and governmental purchasers, and (iii) state activities aimed at increasing price transparency, including new laws as noted above in Item 1. “Competition and the Health Care Environment.” Changes to the health care system enacted as part of health care reform in the U.S., as well as increased purchasing power of entities that negotiate on behalf of Medicare, Medicaid, and private sector beneficiaries, could result in further pricing pressures. As noted in Item 1. “Competition and the Health Care Environment,” in 2023, HHS selected Januvia for the first year of the IRA’s price setting program, which will result in a government set price becoming effective on January 1, 2026. Government price setting may also impact pricing in the private market, negatively affecting the Company’s performance. In January 2025, HHS announced that Janumet and Janumet XR have been selected for government price setting, which will become effective on January 1, 2027. Furthermore, the Company expects that in 2026 HHS will include Keytruda in a subsequent selection of products to undergo IRA price setting, with such price to become effective on January 1, 2028 and the Company expects that, as a result, U.S. sales of Keytruda will decline after that time. In addition, in the U.S., larger customers have received higher rebates on drugs in certain highly competitive categories. The Company must also compete to be placed on formularies of managed care organizations. Exclusion of a product from a formulary can lead to reduced usage in the managed care organization. The Company is also facing pricing pressure from purchasers of certain vaccines in highly competitive categories. Outside the U.S., numerous major markets, including the EU, Japan and China have pervasive government involvement in funding health care and, in that regard, fix the pricing and reimbursement of pharmaceutical and vaccine products. Consequently, in those markets, the Company is subject to government decision making and budgetary actions with respect to its products. In Japan, the pharmaceutical industry is subject to government-mandated annual price reductions of pharmaceutical products and certain vaccines. Furthermore, the Japanese government can order re-pricing for specific products if it determines that use of such product will exceed certain thresholds defined under applicable re-pricing rules. The Company expects pricing pressures to continue in the future.

The Company’s business may be adversely affected by local and global economic conditions, including with respect to inflation, interest rates, and costs of raw materials and packaging. Uncertainty in global economic and geopolitical conditions may result in a slowdown to the global economy that could affect the Company’s business by reducing the prices that drug wholesalers and retailers, hospitals, government agencies and managed health care providers may be able or willing to pay for the Company’s products or by reducing the demand for the Company’s products, which could in turn negatively impact the Company’s sales and result in a material adverse effect on the Company’s business, cash flows, results of operations, financial condition and prospects. As discussed above in Item 1. “Competition and the Health Care Environment,” global efforts toward health care cost containment continue to exert pressure on product pricing and market access worldwide. Changes to the U.S. health care system as part of health care reform, as well as increased purchasing power of entities that negotiate on behalf of Medicare, Medicaid, and private sector beneficiaries, have contributed to pricing pressure. In several international markets, government-mandated pricing actions have reduced prices of generic and patented drugs. In addition, the Company’s sales performance in 2025 was negatively affected by other cost-reduction measures taken by governments and other third parties to lower health care costs, including in the U.S., the expansion of the Federal 340B Drug Discount Program. The Company anticipates all of these actions, and additional actions in the future, will continue to negatively affect sales and profits. 31 31 31 31 31 31 Table of Contents Table of Contents Table of Contents In addition, it is possible that as a consequence of the MFN Agreement, certain of the Company’s products may not be launched in the MFN Countries or their launch may be delayed and as a result, the MFN Countries may take actions that adversely impact the Company. If credit and economic conditions worsen, the resulting economic and currency impacts in the affected markets and globally could have a material adverse effect on the Company’s results.

The Company’s business may be adversely affected by local and global economic conditions, including with respect to inflation, interest rates, and costs of raw materials and packaging. Uncertainty in global economic and geopolitical conditions may result in a slowdown to the global economy that could affect the Company’s business by reducing the prices that drug wholesalers and retailers, hospitals, government agencies and managed health care providers may be able or willing to pay for the Company’s products or by reducing the demand for the Company’s products, which could in turn negatively impact the Company’s sales and result in a material adverse effect on the Company’s business, cash flows, results of operations, financial condition and prospects. 30 30 30 30 30 30 Table of Contents Table of Contents Table of Contents As discussed above in Item 1. “Competition and the Health Care Environment,” global efforts toward health care cost containment continue to exert pressure on product pricing and market access worldwide. Changes to the U.S. health care system as part of health care reform, as well as increased purchasing power of entities that negotiate on behalf of Medicare, Medicaid, and private sector beneficiaries, have contributed to pricing pressure. In several international markets, government-mandated pricing actions have reduced prices of generic and patented drugs. In addition, the Company’s sales performance in 2024 was negatively affected by other cost-reduction measures taken by governments and other third parties to lower health care costs, including in the U.S., the expansion of the Federal 340B Drug Discount Program. The Company anticipates all of these actions, and additional actions in the future, will continue to negatively affect sales and profits. If credit and economic conditions worsen, the resulting economic and currency impacts in the affected markets and globally could have a material adverse effect on the Company’s results.

The risks below are not the only ones the Company faces. Additional risks not currently known to the Company or that the Company presently deems immaterial may also impair its business operations. The Company’s business, financial condition, results of operations, cash flows or prospects could be materially adversely affected by any of these risks. This Form 10-K also contains forward-looking statements that involve risks and uncertainties. The Company’s results could materially differ from those anticipated in these forward-looking statements as a result of certain factors, including the risks it faces described below and elsewhere. See “Cautionary Factors that May Affect Future Results” below.

The risks below are not the only ones the Company faces. Additional risks not currently known to the Company or that the Company presently deems immaterial may also impair its business operations. The Company’s business, financial condition, results of operations, cash flows or prospects could be materially adversely affected by any of these risks. This Form 10-K also contains forward-looking statements that involve risks and uncertainties. The Company’s results could materially differ from those anticipated in these forward-looking statements as a result of certain factors, including the risks it faces described below and elsewhere. See “Cautionary Factors that May Affect Future Results” below. 27 27 27 27 27 27 Table of Contents Table of Contents Table of Contents

The extent of the Company’s operations outside the U.S. is significant. Risks inherent in conducting a global business include: •changes in medical reimbursement policies and programs and pricing restrictions in key markets; •multiple regulatory requirements that could restrict the Company’s ability to manufacture and sell its products in key markets; •trade protection measures and import or export licensing requirements, including the imposition of trade sanctions or similar restrictions by the U.S. or other governments; •the imposition of tariffs by the U.S. or other governments; •foreign exchange fluctuations; •diminished protection of intellectual property in some countries; and •possible nationalization and expropriation. In addition, there may be changes to the Company’s business if there is instability, disruption or destruction in a significant geographic region, regardless of cause, including war, terrorism, riot, civil insurrection or social unrest; and natural or man-made disasters, including famine, flood, fire, earthquake, storm or disease. Events like these, such as the ongoing war between Russia and Ukraine, and conflict in the Middle East, and/or policy changes with respect to international trade protection measures, could result in material adverse effects on 32 32 32 32 32 32 Table of Contents Table of Contents Table of Contents macroeconomic conditions, currency exchange rates and financial markets, and may adversely affect the Company’s business, results of operations, cash flows, financial condition, and prospects.

The extent of the Company’s operations outside the U.S. is significant. Risks inherent in conducting a global business include: •changes in medical reimbursement policies and programs and pricing restrictions in key markets; •multiple regulatory requirements that could restrict the Company’s ability to manufacture and sell its products in key markets; •trade protection measures and import or export licensing requirements, including the imposition of trade sanctions or similar restrictions by the U.S. or other governments; •foreign exchange fluctuations; •diminished protection of intellectual property in some countries; and •possible nationalization and expropriation. The U.S. government has announced plans to significantly increase tariffs on foreign imports into the U.S., particularly from Canada and Mexico and has already increased tariffs on imports from China. It is too early for the 31 31 31 31 31 31 Table of Contents Table of Contents Table of Contents Company to assess if, or to what extent, such policies will be implemented or continue to be implemented, and the extent of any measures that have been or will be taken by any impacted countries. In addition, there may be changes to the Company’s business if there is instability, disruption or destruction in a significant geographic region, regardless of cause, including war, terrorism, riot, civil insurrection or social unrest; and natural or man-made disasters, including famine, flood, fire, earthquake, storm or disease. Events like these, such as the ongoing war between Russia and Ukraine, and the conflict in the Middle East, and/or policy changes with respect to international trade protection measures, could result in material adverse effects on macroeconomic conditions, currency exchange rates and financial markets, and may adversely affect the Company’s business, results of operations, cash flows and financial condition.

The Company depends upon patents to provide it with exclusive marketing rights for its products for some period of time. Loss of patent protection for one of the Company’s products typically leads to a significant and rapid loss of sales for that product as lower priced generic or biosimilar versions become available. In the case of products that contribute significantly to the Company’s sales, the loss of market exclusivity can have a material adverse effect on the Company’s business, cash flows, results of operations, financial condition and prospects. Bridion will lose market exclusivity in the U.S. in July 2026 at which time the Company anticipates a significant and rapid decline in U.S. sales of Bridion. The Company expects to discontinue U.S. sales of Bridion by the end of 2026. In addition, Januvia and Janumet will lose market exclusivity in the U.S. in May 2026 and Janumet XR will lose market exclusivity in the U.S. in July 2026. The Company expects a significant decline in sales of Januvia in the first half of 2026 reflecting the impact of government price setting noted above and subsequently, following loss of market exclusivity in May 2026, the Company anticipates it will lose nearly all U.S. sales of Januvia and Janumet. Also, the Company expects that sales of Keytruda will be materially negatively impacted by biosimilar competition between 2028 and 2029. As previously disclosed, while two patents in the Keytruda composition of matter patent family expire in May and November of 2029, respectively, the Company expects these patents to be the subject of litigation and, thus, biosimilar competition could begin in December 2028 when the primary compound patent expires. The Company also expects to lose market exclusivity in Europe for Keytruda in 2031 following compound patent expiration. There may, however, be attempts by one or more companies to challenge the patent or launch a biosimilar product despite the patent in some European jurisdictions following the expiration of data exclusivity in Europe in July 2026.

The Company depends upon patents to provide it with exclusive marketing rights for its products for some period of time. Loss of patent protection for one of the Company’s products typically leads to a significant and rapid loss of sales for that product as lower priced generic versions of that drug become available. In the case of products that contribute significantly to the Company’s sales, the loss of market exclusivity can have a material adverse effect on the Company’s business, cash flows, results of operations, financial condition and prospects. The Company lost market exclusivity for Bridion in Europe and Japan in 2023 and 2024, respectively, and the Company has experienced a substantial decline in Bridion sales in those markets. Bridion will lose market exclusivity in the U.S. in 2026 (subject to patent litigation discussed below) and the Company expects that sales of Bridion in the U.S. will decline substantially thereafter. In addition, the Company expects U.S. sales of Keytruda to decline beginning in January 2028 upon implementation of government pricing under the IRA, and to further decline upon loss of market exclusivity following expiration of the U.S. compound patent in December 2028. The Company expects to lose market exclusivity in Europe for Keytruda in 2031 following compound patent expiration. There may, however, be attempts by one or more companies to challenge the patent or launch a biosimilar product despite the patent in some European jurisdictions following the expiration of data exclusivity in Europe in July 2026. 28 28 28 28 28 28 Table of Contents Table of Contents Table of Contents

The Company’s business in China experienced significantly lower sales of Gardasil/Gardasil 9 in 2025. Due to above normal inventory levels at the Company’s commercialization partner in China, the Company made a decision to pause shipments to China beginning in February 2025 and has not resumed shipments to date. The Company will not resume shipments until inventory levels return to normal levels and it cannot predict when shipments to China will resume nor the levels of sales that the Company will achieve and as a result, the Company expects that sales of Gardasil/Gardasil 9 in China will not materially increase in 2026. In June 2025, a nine-valent HPV vaccine produced by a local manufacturer received regulatory approval in China for use in females 9-45 years of age. Furthermore, the government's anti-corruption campaign, particularly the increased number of inspections and audits, could substantially increase the administrative burden on health care institutions and health care professionals throughout the whole industry in China and potentially have a negative impact on the Company's sales. In addition to its commercial operations, the Company has significant research and manufacturing operations in China, including working with Chinese entities such as Wuxi Apptech Co., Ltd. If geopolitical tensions were to increase and disrupt the Company’s operations in China, such disruption could result in a material adverse effect on the Company’s product development, sales, business, cash flows, results of operations, financial condition and prospects. Also, growth of the Company’s business in China is dependent upon ongoing development of a favorable environment for innovative pharmaceutical products and vaccines, sustained access for the Company’s currently marketed products, and the absence of trade impediments or adverse pricing controls. As noted above in Item 1. “Competition and the Health Care Environment,” pricing pressure in China has increased as the Chinese government has been taking steps to reduce costs, including implementing health care reform that has led to the acceleration of generic substitution, where available. While the mechanism for drugs being added to the NRDL evolves, inclusion may require a price negotiation which could impact the outlook in the market for selected brands. A new NRDL was recently completed in which new entries averaged approximately 60% price reductions. While pricing pressure has always existed in China, health care reform has increased this pressure in part due to the acceleration of generic substitution through the government’s VBP program. The government has implemented the VBP program through a tendering process for mature products which have generic substitutes with a Generic Quality Consistency Evaluation approval. Mature products that have entered into the latest rounds of VBP had, on average, a price reduction of more than 50%. The Company expects that the VBP process will have a significant impact on mature products moving forward. 34 34 34 34 34 34 Table of Contents Table of Contents Table of Contents

The Company’s business in China has grown in the past few years, and the importance of China to the Company’s overall pharmaceutical and vaccines business has increased accordingly. Beginning in mid-2024, the Company observed a significant decline in shipments from its distributor and commercialization partner in China, Chongqing Zhifei Biological Products Co., Ltd. (Zhifei), to disease and control prevention institutions and correspondingly into the points of vaccination, resulting in above normal inventory levels at Zhifei. Accordingly, the Company shipped less than its contracted doses to Zhifei in the latter part of 2024. Lower demand in China persisted and, at the end of 2024, overall channel inventory levels in China remained elevated at above normal levels. Therefore, the Company made a decision to temporarily pause shipments to China beginning in February 2025 through at least the middle of the year and as a result, combined sales of Gardasil/Gardasil 9 will decline significantly in 2025 compared with 2024. Furthermore, the government's anti-corruption campaign, particularly the increased number of inspections and audits, could substantially increase the administrative burden on health care institutions and health care professionals throughout the whole industry in China and potentially have a negative impact on the Company's sales. In addition to its commercial operations, the Company has significant research and manufacturing operations in China, including working with Chinese entities such as Wuxi Apptech Co., Ltd. If geopolitical tensions were to increase and disrupt the Company’s operations in China, such disruption could result in a material adverse effect on the Company’s product development, sales, business, cash flows, results of operations, financial condition and prospects. Also, continued growth of the Company’s business in China is dependent upon ongoing development of a favorable environment for innovative pharmaceutical products and vaccines, sustained access for the Company’s currently marketed products, and the absence of trade impediments or adverse pricing controls. As noted above in Item 1. “Competition and the Health Care Environment,” pricing pressure in China has increased as the Chinese government has been taking steps to reduce costs, including implementing health care reform that has led to the acceleration of generic substitution, where available. While the mechanism for drugs being added to the NRDL evolves, inclusion may require a price negotiation which could impact the outlook in the market for selected brands. A 33 33 33 33 33 33 Table of Contents Table of Contents Table of Contents new NRDL was recently completed in which new entries averaged 63% price reductions. While pricing pressure has always existed in China, health care reform has increased this pressure in part due to the acceleration of generic substitution through the government’s VBP program. In 2019, the government implemented the VBP program through a tendering process for mature products which have generic substitutes with a Generic Quality Consistency Evaluation approval. Mature products that have entered into the last five rounds of VBP had, on average, a price reduction of more than 50%. The Company expects VBP to be a semi-annual process that will have a significant impact on mature products moving forward.