Sec Form 4 Filing - Kelly Michael Aaron @ Prime Medicine, Inc. - 2025-08-01

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person Kelly Michael Aaron 2. Issuer Name and Ticker or Trading Symbol Prime Medicine, Inc. [ PRME] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O PRIME MEDICINE, INC., 60 FIRST STREET 3. Date of Earliest Transaction (MM/DD/YY) 08/01/2025 (Street) CAMBRIDGE, MA02141 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Stock Option (right to buy) $ 10.54 08/01/2025 D( 1 ) 13,510 ( 2 ) 11/24/2031 Common Stock 13,510 ( 1 ) 0 D Stock Option (right to buy) $ 4.04 08/01/2025 A( 1 ) 13,510 ( 2 ) 11/24/2031 Common Stock 13,510 ( 1 ) 13,510 D Stock Option (right to buy) $ 17 08/01/2025 D( 1 ) 9,006 ( 2 ) 10/19/2032 Common Stock 9,006 ( 1 ) 0 D Stock Option (right to buy) $ 4.04 08/01/2025 A( 1 ) 9,006 ( 2 ) 10/19/2032 Common Stock 9,006 ( 1 ) 9,006 D Stock Option (right to buy) $ 14.83 08/01/2025 D( 1 ) 39,062 ( 2 ) 06/14/2033 Common Stock 39,062 ( 1 ) 0 D Stock Option (right to buy) $ 4.04 08/01/2025 A( 1 ) 39,062 ( 2 ) 06/14/2033 Common Stock 39,062 ( 1 ) 39,062 D Stock Option (right to buy) $ 7.68 08/01/2025 D( 1 ) 45,000 ( 2 ) 06/12/2034 Common Stock 45,000 ( 1 ) 0 D Stock Option (right to buy) $ 4.04 08/01/2025 A( 1 ) 45,000 ( 2 ) 06/12/2034 Common Stock 45,000 ( 1 ) 45,000 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Kelly Michael Aaron C/O PRIME MEDICINE, INC. 60 FIRST STREET CAMBRIDGE, MA02141 X Signatures /s/ Ryan Brown, attorney-in-fact 08/05/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Effective as of August 1, 2025 (the "Repricing Date"), the Issuer's stockholders approved a one-time repricing of certain outstanding stock options (the "Repriced Options") granted under the Issuer's 2019 Stock Option and Grant Plan, as amended (the "2019 Plan") and/or the 2022 Stock Option and Incentive Plan (the "2022 Plan" and, together with the 2019 Plan, the "Plans"), which reduced the per share exercise price of each Repriced Option to $4.04, representing the closing price of the Issuer's common stock on The Nasdaq Global Market on the Repricing Date (the "Option Repricing"). Except as modified by the Option Repricing, all other terms and conditions of the Repriced Options, including, without limitation, any provisions with respect to vesting and term of the Repriced Options, remain in full force and effect. ( 2 )This stock option award was issued pursuant to the 2019 Plan and/or the 2022 Plan, as applicable, and becomes exercisable in accordance with the vesting schedule specified in the award agreement and as previously reported on applicable Form 4, subject to the Reporting Person's continued service with the Issuer as of the applicable vesting date.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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