SCHEDULE 13G/A

Prime Medicine Inc

Common Stock, par value $0.00001 per share · CUSIP: 74168J101

Event date: 2025-09-30

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• GV 2019, L.P.

  Shares: 10,100,058.00 · Class: 7.5%

• GV 2019 GP, L.P.

  Shares: 10,100,058.00 · Class: 7.5%

• GV 2019 GP, L.L.C.

  Shares: 10,100,058.00 · Class: 7.5%

• GV 2021, L.P.

  Shares: 3,262,440.00 · Class: 2.4%

• GV 2021 GP, L.P.

  Shares: 3,262,440.00 · Class: 2.4%

• GV 2021 GP, L.L.C.

  Shares: 3,262,440.00 · Class: 2.4%

• GV 2023, L.P.

  Shares: 3,200,000.00 · Class: 2.4%

• GV 2023 GP, L.P.

  Shares: 3,200,000.00 · Class: 2.4%

• GV 2023 GP, L.L.C.

  Shares: 3,200,000.00 · Class: 2.4%

• Alphabet Holdings LLC

  Shares: 16,562,498.00 · Class: 12.3%

• XXVI Holdings Inc.

  Shares: 16,562,498.00 · Class: 12.3%

• Alphabet Inc.

  Shares: 16,562,498.00 · Class: 12.3%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.