Form of stock option terms for 2023 annual non-qualified option grants under the Merck & Co., Inc. 2019 Incentive Stock Plan

A.    Vesting & Expiration Dates. This stock option becomes exercisable in equal installments (subject to a rounding process) on the Vesting Dates indicated in the box above. This stock option expires on its Expiration Date, which is the day before the tenth anniversary of the Grant Date. If your employment with the Company or, if different, the subsidiary, affiliate or joint venture (“JV”) of the Company by which you are employed (the “Employer”) is terminated, your right to exercise this stock option will be determined according to the terms in Section II and for grantees outside the United States, also in paragraph 12 of Section A (“Nature of Grant”) of Appendix B, Part I.

B.    Subject to Recoupment. This stock option will be subject to recoupment in the event of certain violations of Company policy in accordance with the Company’s Policies and Procedures for Recoupment of Compensation for Compliance Violations and for Significant Restatement of Financial Results, as set forth in Appendix A (as may be amended from time to time).

A.General Rule. If your employment is terminated for any reason other than those specified in the following paragraphs, the portion of this stock option that is unvested will expire on the date your employment ends (for avoidance of doubt, if your employment terminates on a Vesting Date not for misconduct, you will be entitled to vest in that unvested portion of the stock option that is scheduled to vest on that Vesting Date); the portion of this stock option that is vested will expire unless exercised before the New York Stock Exchange closes (the “Close of Business”) on the same day of the third month (“Within Three Months”) after the date of the termination (but in no event after the expiration of the Option Period). Close of Business for any day on which the New York Stock Exchange is not open

means the close of business prior to that date when the Exchange is open. Where there is no corresponding day of a month, the last day of the month is deemed to be the same day as a later date (e.g., November 28, 29 and 30 all correspond to February 28 in non-leap years). If you are rehired by the Company or the Employer, as applicable, this option nevertheless will expire unless exercised Within Three Months, or the original Expiration Date if earlier.

B.Involuntary Termination. If the Company determines that your employment is involuntarily terminated, including the result of a restructuring or job elimination, but excluding non-performance of your duties and the reasons listed under paragraphs C through H, the portion of this stock option that is unvested will expire on the date your employment ends (for avoidance of doubt, if your employment terminates on a Vesting Date not for misconduct, you will be entitled to vest in that unvested portion of the stock option that is scheduled to vest on that Vesting Date); the portion of this stock option that is vested will expire on the one year anniversary of the date your employment ends, but in no event later than the original Expiration Date. If your employment is terminated as described in this paragraph and you are later rehired by the Company or the Employer, as applicable, this option nevertheless will expire according to this paragraph notwithstanding such rehire.

C.Sale. If your employment is terminated and the Company determines that such termination resulted from the sale of your subsidiary, affiliate, division or JV, the following portion of this stock option award will vest and become exercisable immediately upon such termination: if employment terminates on or after the Grant Date but before the first anniversary thereof, then one-third of this stock option award will vest and become exercisable; if employment terminates on or after the first anniversary of the Grant Date, then all unvested stock options will vest and become exercisable. The remaining portion, if any, of this stock option that does not vest pursuant to the foregoing sentence will be forfeited on the date your employment terminates. Whether already vested on the date your employment terminates or vested as a result of such sale, this stock option will expire on the first anniversary of the date your employment with the Company or the Employer, as applicable, ends, but in no event later than the original Expiration Date. Notwithstanding the foregoing, the Committee may determine, for purposes of this stock option grant, whether employment with an entity that is established from the Company’s spin off, split off, split up or distribution of equity securities in connection with that entity constitutes a  termination of employment, and may make adjustments, if any, as it deems appropriate, and not inconsistent with the Plan, at the time of the distribution of such equity securities, in the kind and/or number of shares subject to this option, and/or in the option price of such option. If your employment is terminated as described in this paragraph and you are later rehired by the Company or the Employer, as applicable, this option nevertheless will expire according to this paragraph notwithstanding such rehire.

D.Retirement. If your employment terminates as the result of your retirement, the portion of this stock option that would have become exercisable according to its original schedule within one year of the date your employment terminates will vest and become exercisable on its applicable Vesting Date and the remainder will expire immediately. Whether already vested on the date your employment terminates or vested as a result of such retirement, this option will expire on the earlier of (a) the fifth anniversary of the termination date or (b) its original Expiration Date. For grantees who are employed in the U.S., “retirement” means a termination of employment after attaining the earliest of (a) age 55 with at least 10 years of service (b) such age and service that provides eligibility for subsidized retiree medical coverage or (c) age 65 without regard to years of service. For other grantees, “retirement” is determined by the Company. If your employment is terminated as described in this paragraph and you are later rehired by the Company or the Employer, as applicable, this option nevertheless will expire according to this paragraph notwithstanding such rehire.

E.Death. If your employment terminates as a result of your death, the portion of this stock option that is unvested will vest immediately upon your death. Whether already vested on the date of your death or vested as a result of your death, this stock option will expire on the second anniversary of your death,

even if such date is later than the Original Expiration date. This stock option will expire on such earlier date than otherwise specified in this paragraph as may be required under applicable non-U.S. law. If you die while any portion of this stock option remains outstanding, but after your employment terminates for the reasons listed under paragraphs B, C, D, G or H of this section, the portion that remains outstanding after such employment termination will become immediately exercisable and will continue to be exercisable until the expiration date prescribed in paragraph B, C, D, G or H as applicable (and at least a year from your death in those jurisdictions where such extension is required by law).

F.Misconduct. If your employment is terminated as a result of your deliberate, willful or gross misconduct, this stock option (whether vested or unvested) will expire immediately upon your receipt of notice of such termination.

G.Disability. If your employment is terminated and the Company determines that such termination resulted from your inability to perform the material duties of your role by reason of a physical or mental infirmity that is expected to last for at least six months or to result in your death, whether or not you are eligible for disability benefits from any applicable disability program, then this stock option will continue to become exercisable on applicable Vesting Dates and will expire on the earlier of (a) the fifth anniversary of the day your employment terminates and (b) its original Expiration Date. If your employment is terminated as described in this paragraph and you are later rehired by the Company or the Employer, as applicable, this option nevertheless will expire according to this paragraph notwithstanding such rehire.

H.Change in Control. If this stock option is assumed, converted or otherwise remains outstanding in connection with a Change in Control and your employment is involuntarily terminated without Cause before the second anniversary after the closing of a Change in Control, each unvested stock option that is outstanding immediately prior to the Change in Control will immediately become fully vested and exercisable. All options, including options vested prior to such time, will expire on the fifth anniversary of the termination of your employment following a Change in Control (but not beyond the Expiration Date). This extended exercise period does not apply in the case of termination by reasons of retirement, involuntary termination, sale, misconduct, death or disability, as described in paragraphs B through G above or termination prior to a Change in Control. If this stock option does not remain outstanding following the Change in Control and is not converted into a successor stock option, then each unvested stock option that is outstanding immediately prior to the Change in Control will lapse as of the Change in Control and at the election of the Company, you will be entitled to receive cash for this stock option in an amount at least equal to the difference between the price paid to stockholders in the Change in Control and the Option Price of this stock option. “Cause” and “Change in Control” are defined in the Merck & Co., Inc. Change in Control Separation Benefits Plan (excluding an MSD Change in Control).

I.Transfer of Employment. Transfer of employment between the Company, a subsidiary, affiliate, JV, JV partner or affiliate of the Company who provides services to the JV with such partner or affiliate or other entity in which the Company has determined that it has a significant business or ownership interest (together, the “Company Group”) is not considered termination of employment for purposes of this stock option. Such employment must be approved by the Company and contiguous with employment by the entity in the Company Group you were employed by immediately prior to the relevant transfer. The terms set out in paragraphs A through H above shall continue to apply to this stock option following a transfer of employment accordance with this section.

This stock option and any interest therein shall not be sold, assigned, transferred, pledged or otherwise disposed of, alienated or encumbered, either voluntarily or involuntarily, other than by will or the laws of descent and distribution in connection with your death.

Regardless of any action the Company and/or the Employer take with respect to any or all income tax, social insurance, payroll tax, payment on account or other tax-related items arising out of your participation in the Plan and legally applicable or deemed applicable to you (“Tax-Related Items”), you acknowledge that the ultimate liability for all Tax-Related Items is and remains your responsibility and may exceed the amount actually withheld by the Company and/or the Employer, if any. You further acknowledge that the Company and/or the Employer (i) make no representations or undertakings regarding the treatment of any Tax-Related Items in connection with any aspect of the stock option or underlying shares of Common Stock, including, but not limited to, the grant, vesting or exercise of the stock option, the subsequent sale of shares of Common Stock acquired pursuant to such exercise and the receipt of any dividends; and (ii) do not commit and are under no obligation to structure the terms of the grant or any aspect of the stock option to reduce or eliminate your liability for Tax-Related Items or achieve any particular tax result. Furthermore, if you have become subject to tax in more than one jurisdiction, you acknowledge that the Company and/or the Employer (or former employer, as applicable) may be required to withhold or account for Tax-Related Items in more than one jurisdiction.

Prior to the relevant taxable or tax withholding event, as applicable, you shall pay or make arrangements satisfactory to the Company and/or the Employer to satisfy any applicable withholding obligations or rights with regard to all Tax-Related Items. In this regard, you authorize the Company and/or the Employer, or their respective agents, at their discretion, to satisfy the Tax-Related Items by one or a combination of the following: (i) withholding from your wages or other cash compensation paid to you by the Company, the Employer and/or any subsidiary, affiliate or JV of the Company; or (ii) withholding from proceeds of the sale of shares of Common Stock acquired at exercise of the stock option either through a voluntary sale or through a mandatory sale arranged by the Company (on your behalf pursuant to this authorization); or (iii) withholding in shares of Common Stock to be issued at exercise of the stock option; provided, however, that if you are a Section 16 officer of the Company under the Exchange Act, then the Committee must approve any decision to satisfy the Tax-Related Items by the method described in (iii) above.

The Company may withhold or account for Tax-Related Items by considering applicable minimum statutory withholding amounts or other applicable withholding rates, including maximum applicable rates in your jurisdiction(s). In the event of over-withholding, you may receive a refund of any over-withheld amount in cash (with no entitlement to the equivalent in common stock), or if not refunded, you may seek a refund from the local tax authorities. In the event of under-withholding, you may be required to pay additional Tax-Related Items directly to the applicable tax authority or to the Company and/or the Employer. If the obligation for Tax-Related Items is satisfied by withholding in shares of Common Stock, for tax purposes, you will be deemed to have been issued the full number of shares of Common Stock subject to the exercised stock options, notwithstanding that a number of the shares is held back solely for the purpose of paying the Tax-Related Items due as a result of any aspect of your participation in the Plan.

You shall pay to the Company or the Employer any amount of Tax-Related Items that the Company or the Employer may be required to withhold or account for as a result of your participation in the Plan that cannot be satisfied by the means previously described in this section. The Company may refuse to issue or deliver the shares of Common Stock or the proceeds of the sale of shares, if you fail to comply with your obligations in connection with the Tax-Related Items.

The Company is located at 126 East Lincoln Avenue, P.O. Box 2000, Rahway, NJ 07065, U.S.A. and grants employees of the Company and any subsidiary, affiliate or JV of the Company, the opportunity to participate in the Plan, at the Company's sole discretion. If you would like to participate in the Plan, you understand that you should review the following information about the Company’s data processing practices and declare your consent.

A.Data Collection and Usage. The Company collects, processes and uses your personal data, including, name, home address, email address and telephone number, date of birth, social insurance number or other identification number, salary, citizenship, job title, any shares of Common Stock or directorships held in the Company, and details of all awards, canceled, vested, or outstanding in your favor, which the Company receives from you or your Employer. If the Company offers you the opportunity to participate in the Plan, then the Company will collect your personal data for purposes of allocating Common Stock and implementing, administering and managing the Plan. The Company’s legal basis for the processing of your personal data would be your consent.

B.Stock Plan Administration Service Providers. The Company transfers participant data to Morgan Stanley, an independent service provider based in the United States, which assists the Company with the implementation, administration and management of the Plan. In the future, the Company may select a different service provider and share your data with another company that serves in a similar manner. The Company’s service provider will open an account for you. You will be asked to agree on separate terms and data processing practices with the service provider, which is a condition to your ability to participate in the Plan.

C.International Data Transfers. The Company and its service providers are based in the United States. If you are outside of the United States, you should note that your country has enacted data privacy laws that are different from the United States. The Company’s legal basis for the transfer of your personal data is your consent.

D.Voluntariness and Consequences of Consent Denial or Withdrawal. Your participation in the Plan and your grant of consent is purely voluntary. You may deny or withdraw your consent at any time. If you do not consent, or if you withdraw your consent, you cannot participate in the Plan. This would not affect your salary as an employee; you would merely forfeit the opportunities associated with the Plan.

E.Data Subject Rights. You have a number of rights under data privacy laws in your country. Depending on where you are based, your rights may include the right to (i) request access or copies of personal data the Company processes, (ii) rectification of incorrect data, (iii) deletion of data, (iv) restrictions on processing, (v) portability of data, (vi) to lodge complaints with competent authorities in your country, and/or (vii) a list with the names and addresses of any potential recipients of the your personal data. To receive clarification regarding your rights or to exercise your rights please contact the Company at Attn: Global Privacy Office, 351 N. Sumneytown Pike, North Wales, Pennsylvania, U.S.A. 19454.

F.The collection, use and transfer of your personal data for the purpose of implementing, administering and managing your participation in the Plan is conducted in accordance with the Company’s Global Privacy and Data Protection Policy. You also understand that the Company may, in the future, request you to provide another data privacy consent.  If applicable and upon request of the Company, you agree to provide an executed acknowledgement or data privacy consent form to the Company or the Employer (or any other acknowledgements, agreements or consents) that the Company and/or the Employer may deem necessary to obtain under the data privacy laws in your country, either now or in the future.  You understand that you will not be able to participate in the Plan if you fail to execute any such acknowledgement, agreement or consent requested by the Company and/or the Employer.

If you agree with the data processing practices described in this Section, you will declare your consent by clicking to "Accept" these Terms on the Morgan Stanley website.

This document may be amended only by another written agreement between the parties. This document will be interpreted and enforced under the laws of the State of New Jersey, United States (without regard to its choice-of-law provisions). For purposes of litigating any dispute that arises directly or indirectly from the relationship of the parties evidenced by this grant or this document, the parties hereby submit to and consent to the exclusive jurisdiction of the State of New Jersey and agree that such litigation shall be conducted only in the courts of Union County, New Jersey, or the federal courts for the United States for the District of New Jersey, and no other courts, where this grant is made and/or to be performed.

The provisions of this document are severable and if any one or more provisions are determined to be illegal or otherwise unenforceable, in whole or in part, the remaining provisions shall nevertheless be binding and enforceable.

You acknowledge that a waiver by the Company of breach of any provision of these Terms shall not operate or be construed as a waiver of any other provision of these Terms or of any subsequent breach by you or any other grantee.

The Company may, in its sole discretion, decide to deliver any documents related to the stock option or future options that may be granted under the Plan by electronic means or request your consent to participate in the Plan by electronic means. You hereby consent to receive such documents by electronic delivery and agree to participate in the Plan through an online or electronic system established and maintained by the Company or a third party designated by the Company.

This stock option shall be subject to any additional provisions set forth in Appendix B for your country, if any. If you relocate to one of the countries included in Appendix B during the life of this stock option, the additional provisions for such country shall apply to you, to the extent the Company determines that the application of such provisions is necessary or advisable in order to comply with local law or facilitate the administration of the Plan.

The Committee is responsible for construing and interpreting this stock option, including the right to construe disputed or doubtful Plan provisions, and may establish, amend and construe such rules and regulations as it may deem necessary or desirable for the proper administration of this stock option grant. Any decision or action taken or to be taken by the Committee, arising out of or in connection with the construction, administration, interpretation and effect of this stock option grant shall, to the maximum extent permitted by applicable law, be within its absolute discretion (except as otherwise specifically provided herein) and shall be final, binding and conclusive upon the Company, all Eligible Employees and any person claiming under or through any eligible employee. All determinations by the Committee including, without limitation, determinations of the Eligible Employees, the form, amount and timing of incentives, the terms and provisions of incentives and the writings evidencing incentives, need not be uniform and may be made selectively among Eligible Employees who receive, or are eligible to receive, Incentives hereunder, whether or not such Eligible Employees are similarly situated.

This stock option is subject to the provisions of the 2019 Incentive Stock Plan. For further information regarding your stock options, you may access the Merck Global Long-Term Incentives homepage via Sync > HR > Money > Long-Term Incentive Program.

This Appendix, which is part of the Global Terms and Conditions for 2023 Non-Qualified Stock Option Grants under the Merck & Co., Inc. 2019 Incentive Stock Plan, contains additional “terms and conditions” that will apply to you if you reside outside the United States.

The terms and conditions in Part I of this Appendix apply to all grantees who reside outside the United States. The additional terms and conditions in Part II of this Appendix will also apply to you if you reside in one of the countries referenced in Part II.

The information in this Appendix is based on the laws in effect in the respective countries as of April 2023. Such laws are often complex and change frequently. As a result, the Company strongly recommends that you not rely on the information in this Appendix as the only source of information relating to the consequences of your participation in the Plan because the information may be out of date at the time that the stock option vests, you exercise the stock option and shares of Common Stock are issued to you or you sell shares of Common Stock acquired upon exercise of the stock option under the Plan.

In addition, the information contained in this Appendix is general in nature and may not apply to your particular situation, and the Company is not in a position to assure you of a particular result. Accordingly, you should seek appropriate professional advice as to how the relevant laws in your country may apply to your situation.

Finally, if you are a citizen or resident of a country, or are considered a resident of a country, other than that in which you are currently working, or transfer residence and/or employment after the Grant Date, the information contained herein may not apply to you in the same manner. The Company shall, in its sole discretion, determine to what extent the terms and conditions included herein will apply under these circumstances.

The following additional terms and conditions will apply to you if you reside in any country outside the United States.

In accepting the stock option, you acknowledge and agree that:

1.the Plan is established voluntarily by the Company, is discretionary in nature, and may be amended, suspended, or terminated by the Company at any time;

2.the grant of the stock option is exceptional, voluntary, and occasional and does not create any contractual or other right to receive future grants of stock options, or benefits in lieu of stock options, even if stock options have been granted in the past;

3.all decisions with respect to future stock option grants, if any, will be at the sole discretion of the Company;

4.your participation in the Plan is voluntary;

5.your participation in the Plan shall not create a right to employment or be interpreted as forming or amending an employment or service contract with the Company and shall not interfere with the ability of the Employer to terminate your employment or service relationship (if any) at any time;

6.the stock option and any shares of Common Stock acquired under the Plan, and the income from and value of same, are extraordinary items that do not constitute compensation of any kind for services of any kind rendered to the Employer, the Company, or any subsidiary, affiliate, or JV of the Company, and that are outside the scope of your employment or service contract, if any;

7.unless otherwise agreed with the Company in writing, the stock option and any shares of Common Stock acquired under the Plan, and the income and value of same, are not granted as consideration for, or in connection with, the service you may provide as a director of a subsidiary, affiliate, or JV of the Company;

8.the stock option and any shares of Common Stock acquired under the Plan, and the income from and value of same, are not intended to replace any pension rights or compensation;

9.the stock option and any shares of Common Stock acquired under the Plan, and the income from and value of same, are not part of normal or expected compensation or salary for any purposes, including, but not limited to, calculating any severance, resignation, termination, redundancy, dismissal, end of service payments, bonuses, long-service awards, pension or retirement or welfare benefits or similar payments and in no event should be considered as compensation for, or relating in any way to, past services for the Employer, the Company or any subsidiary, affiliate or JV of the Company;

10.the future value of the shares of Common Stock underlying the stock option is unknown, indeterminable and cannot be predicted with certainty;

11.if the underlying shares of Common Stock do not increase in value, the stock option will have no value;

12.if you exercise the stock option and acquire shares of Common Stock, the value of such shares of Common Stock may increase or decrease in value, even below the Option Price;

13.no claim or entitlement to compensation or damages shall arise from termination of the stock option resulting from termination of your employment by the Company or the Employer (for any reason whatsoever and whether or not in breach of the employment laws in the jurisdiction where you are employed or the terms of your employment agreement, if any);

14.for purposes of the stock option, your employment relationship will be considered terminated as of the date you are no longer providing services to the Employer or the Company or any subsidiary, affiliate or JV of the Company (regardless of the reason for such termination and whether or not later found to be invalid or in breach of the employment laws in the jurisdiction where you are employed or the terms of your employment agreement, if any), and unless otherwise expressly provided in this document, your right to vest in the stock option under the Plan, if any, will terminate effective as of such date and will not be extended by any notice period or any period of “garden leave” or similar period mandated under local; similarly, any right to exercise the stock option after termination of employment will be measured as of the date you are no longer providing services to the Employer or the Company or any subsidiary, affiliate or JV and will not be extended by any notice period or any period of “garden leave” or similar period mandated under local law; the Committee shall have the exclusive discretion to

determine when you are no longer providing services for purposes of the grant (including whether you may still be considered to be providing services while on a leave of absence);

15.the stock option and the benefits under the Plan, if any, will not automatically transfer to another company in the case of a merger, take-over or transfer of liability;

16.the Company is not providing any tax, legal or financial advice, nor is the Company making any recommendation regarding your participation in the Plan, or the acquisition or sale of underlying shares; you should consult with your personal tax, legal, and financial advisors regarding the decision to participate in the Plan and before taking any action related to the Plan; and

17.neither the Employer, nor the Company or any subsidiary, affiliate, or JV shall be liable for any foreign exchange rate fluctuation between your local currency and the United States Dollar that may affect the value of the stock option or any amounts due to you pursuant to the exercise of the stock option, the subsequent sale of shares acquired under the Plan or the receipt of any dividends.

You acknowledge that, depending on your or your broker’s country of residence or where shares of Common Stock are listed, you may be subject to insider trading restrictions and/or market abuse laws, which may affect your ability to accept, acquire, sell or otherwise dispose of shares of Common Stock, rights to shares of Common Stock (e.g., stock options) or rights linked to the value of shares of Common Stock under the Plan during such times that you are considered to have “inside information” regarding the Company (as defined by the laws or regulations in the applicable jurisdictions or your country). Local insider trading laws and regulations may prohibit the cancellation or amendment of orders you placed before you possessed inside information. Furthermore, you could be prohibited from (i) disclosing the inside information to any third party and (ii) “tipping” third parties or causing them otherwise to buy or sell securities. You should keep in mind that third parties include fellow employees. Any restrictions under these laws or regulations are separate from and in addition to any restrictions that may be imposed under any applicable Company insider trading policy. You understand you are responsible for ensuring compliance with any restrictions and should consult with your personal legal advisor on this matter.

You acknowledge that, depending on your country, you may be subject to foreign asset/account, exchange control and/or tax reporting requirements as the result of the acquisition of shares of Common Stock or cash (including dividends and the proceeds of the sale of shares of Common Stock) derived from your participation in the Plan, in, to and/or from a brokerage/bank account or legal entity located outside your country. The applicable laws of your country may require that you report such accounts, assets, the balances therein, the value thereof and/or the transactions related thereto to the applicable authorities in your country. You may also be required to repatriate cash received from participating in the Plan to your country within a certain time after receipt. You acknowledge that you are responsible for ensuring compliance with any applicable foreign asset/account, exchange control and tax reporting requirements and should consult your personal tax, legal and/or financial advisors regarding the same.

You acknowledge that you are proficient in the English language, or have consulted with an advisor who is sufficiently proficient, to allow you to understand the terms and conditions of this document. If you have received this document, or any other document related to the stock option and/or the Plan translated into a language other than English, and if the translated version is different than the English version, the English version will control unless otherwise required by local law.

The Company reserves the right to impose other requirements on the stock option and the shares of Common Stock purchased upon exercise of the stock options, to the extent the Company determines it is necessary or advisable to comply with local laws or facilitate the administration of the Plan, and to require you to sign any additional agreements or undertakings that may be necessary to accomplish the foregoing.

In particular, if advisable due to local law requirements, the Committee, in its sole and absolute discretion, may restrict the methods of exercise available such that, for example, you may be required to immediately sell all of the shares of Common Stock underlying the exercised stock option and will receive only the sale proceeds less the Option Price and any applicable Tax-Related Items.