Foster-Cheek Kaye I 4

What Happened

• Kaye Foster-Cheek, a director of Prime Medicine, was granted a derivative award (option) covering 75,000 shares on June 5, 2026. The reported acquisition price is $0.00 (i.e., a grant/award rather than an open-market purchase or sale).
• This is a grant of equity compensation, not a sale or cash purchase. No exercise or sale occurred in this filing.

Key Details

• Transaction date: 2026-06-05; filing date: 2026-06-08 (filed within the normal Form 4 timing).
• Transaction type/code: A = Grant/Award (derivative option); reported price: $0.00.
• Shares acquired: 75,000 optioned shares. Post-transaction total beneficial ownership is not specified in the provided excerpt.
• Footnote: The shares underlying the option vest in full upon the earlier of (i) June 5, 2027 or (ii) the date of the next annual meeting of stockholders, subject to Foster-Cheek’s continued service.
• No indication in this filing of exercise, sale, tax withholding, or a 10b5-1 plan.

Context

• Director equity grants are a common form of compensation to align incentives with shareholders; they do not reflect an immediate market purchase or sale.
• Because this is a grant (option award) with a vesting schedule, it signals compensation arrangement rather than a direct trading view by the insider.