[Form 4] Prime Medicine, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Prime Medicine (PRME) Form 4: Director Thomas Cahill reported a one-time repricing of four previously granted stock-option blocks on 08/01/2025. Options carrying exercise prices of $14.83 (39,062 shares) and $7.68 (45,000 shares) were cancelled (Code D) and simultaneously re-granted at $4.04 (Code A) for identical share amounts and original expirations (06/14/2033 and 06/12/2034, respectively). The new price equals PRME’s Nasdaq closing price on the repricing date, as approved by stockholders under the 2019 and 2022 equity plans. All vesting schedules and terms remain unchanged. Following the transactions, Cahill beneficially owns 84,062 options at the reduced strike, all held directly.

No open-market share movement or cash consideration occurred; the filing solely reflects the governance-approved adjustment intended to restore incentive value after a share-price decline.

Positive

• Shareholder approval secured for the option repricing, reducing governance risk.
• Repricing realigns director incentives with current share price without increasing option count.

Negative

• Option repricing may be viewed as rewarding underperformance, raising governance concerns.
• Lower strike price could diminish potential upside for existing shareholders if options become in-the-money.

Insights

Equity Compensation Analyst

TL;DR: Director’s underwater options reset to $4.04, preserving 84k options; alignment improved, dilution unchanged.

The Form 4 documents a classic stock-option repricing. Because old grants were surrendered and re-issued at market price, there is no incremental share count or immediate P&L impact, but the options are far closer to being in-the-money, enhancing retention incentives. Shareholder approval mitigates governance risk; however, such actions can still be viewed unfavorably by investors who prefer performance-based resets. Overall market impact is minor given the limited share quantity versus PRME’s float.

Corporate Governance Specialist

TL;DR: Shareholder-approved repricing is procedurally sound; perception depends on views of option reset fairness.

Repricing underwater options often draws scrutiny, yet the board obtained stockholder consent, aligning with best-practice transparency. No acceleration of vesting or term extension occurred. While the action bolsters executive motivation amid a depressed stock price, some governance purists may deem it a reward for poor performance. The modest size suggests not impactful to capitalization but sets a precedent for future resets.

SEC Form 4

FORM 4

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
or Section 30(h) of the Investment Company Act of 1940

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

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Cahill Thomas

(Last) (First) (Middle)

C/O PRIME MEDICINE, INC.

60 FIRST STREET

(Street)

CAMBRIDGE MA 02141

(City) (State) (Zip)

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)

3. Date of Earliest Transaction (Month/Day/Year)
08/01/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	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 (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (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: 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)	$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

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.

Remarks:

	/s/ Ryan Brown, attorney-in-fact	08/05/2025
	** Signature of Reporting Person	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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FAQ

What did Prime Medicine (PRME) report in this Form 4?

Director Thomas Cahill exchanged previously issued stock options for new options repriced to $4.04 per share.

How many options were affected by the repricing?

A total of 84,062 options (39,062 + 45,000) were cancelled and re-granted at the lower exercise price.

Does the repricing change the expiration dates or vesting schedules?

No. All original vesting terms and expiration dates (2033 and 2034) remain intact.

Was shareholder approval required for this option repricing?

Yes. The filing states that stockholders approved the one-time repricing on 08/01/2025.

Is there any immediate cash impact to Prime Medicine?

No cash changes hands; the filing reflects only the strike-price adjustment on previously granted options.