Thomas Cahill - 01 Aug 2025 Form 4 Insider Report for Prime Medicine, Inc. (PRME)

Role: Director
Signature: /s/ Ryan Brown, attorney-in-fact
Issuer symbol: PRME
Transactions as of: 01 Aug 2025
Net transactions value: $0
Form type: 4
Filing time: 05 Aug 2025, 20:42:47 UTC
Previous filing: 05 Jun 2025
SEC: View on sec.gov

Reporting Owners (1)

Name	Relationship	Address	Signature	Signature date	CIK
Cahill Thomas	Director	C/O PRIME MEDICINE, INC., 60 FIRST STREET, CAMBRIDGE	/s/ Ryan Brown, attorney-in-fact	05 Aug 2025	0001922939

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type	Sym	Class	Transaction	Shares	Change %	Shares After	Date	Underlying Class	Amount	Exercise Price	Ownership	Footnotes
transaction	PRME	Stock Option (right to buy)	Disposed to Issuer	-39,062	-100%	0	01 Aug 2025	Common Stock	39,062	$14.83	Direct	F1, F2
transaction	PRME	Stock Option (right to buy)	Award	+39,062		39,062	01 Aug 2025	Common Stock	39,062	$4.04	Direct	F1, F2
transaction	PRME	Stock Option (right to buy)	Disposed to Issuer	-45,000	-100%	0	01 Aug 2025	Common Stock	45,000	$7.68	Direct	F1, F2
transaction	PRME	Stock Option (right to buy)	Award	+45,000		45,000	01 Aug 2025	Common Stock	45,000	$4.04	Direct	F1, F2

* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id	Content
F1	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.
F2	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.

Content

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.

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.