SEC Form SC 13G/A filed by Prime Medicine Inc. (Amendment)

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Schedule 13G

Under the Securities Exchange Act of 1934

(Amendment No. 2)*

Prime Medicine, Inc.

(Name of Issuer)

Common Stock, par value $0.00001 per share

(Title of Class of Securities)

74168J101

(CUSIP Number)

February 20, 2024

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

The information required in the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

This Amendment No. 2 (this “Amendment”) amends the statement on Schedule 13G initially filed by certain of the Reporting Persons (as defined in Item 2(a) below) on February 10, 2023 with the Securities and Exchange Commission (the “SEC”), as amended by Amendment No. 1, filed on February 9, 2024. This Amendment is being filed to report the Reporting Persons’ reliance, effective as of February 20, 2024 (the “Event Date”) on the exemption afforded by Rule 13d-1(c), promulgated under the Securities Exchange Act of 1934, as amended (the “Exchange Act”), in connection with the Reporting Persons’ acquisition of an additional 2% or more of the Issuer’s (as defined in Item 1(a) below) registered class of securities, in the aggregate, within the trailing 12 month period preceding the Event Date.

Prime Medicine, Inc. (the “Issuer”)

21 Erie Street

Cambridge, MA 02139

GV 2019, L.P., a Delaware limited partnership (the “2019 Partnership”)

GV 2019 GP, L.P., a Delaware limited partnership (“2019 GP”)

GV 2019 GP, L.L.C., a Delaware limited liability company (“2019 LLC”)

GV 2021, L.P., a Delaware limited partnership (the “2021 Partnership”)

GV 2021 GP, L.P., a Delaware limited partnership (“2021 GP”)

GV 2021 GP, L.L.C., a Delaware limited liability company (“2021 LLC”)

GV 2023, L.P., a Delaware limited partnership (the “2023 Partnership”)

GV 2023 GP, L.P., a Delaware limited partnership (“2023 GP”)

GV 2023 GP, L.L.C., a Delaware limited liability company (“2023 LLC”)

Alphabet Holdings LLC, a Delaware limited liability company (“Alphabet Holdings”)

XXVI Holdings Inc., a Delaware corporation (“XXVI”), and

Alphabet Inc., a Delaware corporation (“Parent” and, together with the 2019 Partnership, 2019 GP, 2019 LLC, the 2021 Partnership, 2021 GP, 2021 LLC, the 2023 Partnership, 2023 GP, 2023 LLC, Alphabet Holdings, and XXVI, the “Reporting Persons”).

The address of the principal business office of each of the Reporting Persons is:

1600 Amphitheatre Parkway Mountain View, CA 94043

Each of the Reporting Persons is formed, organized or incorporated, as applicable, in the State of Delaware.

Common Stock, par value $0.00001 per share

74168J101

Reference to “beneficial ownership” of securities for purposes of this Amendment shall be understood to refer to beneficial ownership as that term is defined in Rule 13d-3 of the Exchange Act.

As of the Event Date, which is the date as of which the Reporting Persons became obligated to file this Amendment, the Reporting Persons may be deemed to beneficially own an aggregate 15,062,498 shares of the Issuer’s Common Stock.

As of the Event Date, the 2019 Partnership was the direct beneficial owner of 10,100,058 of the shares of Common Stock described in the preceding paragraph. 2019 GP is the general partner of the 2019 Partnership, and 2019 LLC is the general partner of 2019 GP. As such, 2019 GP and 2019 LLC may each be deemed to indirectly beneficially own the securities that are directly beneficially owned by the 2019 Partnership.

As of the Event Date, the 2021 Partnership was the direct beneficial owner of 1,762,440 shares of Common Stock described in the second paragraph of this Item 4(a). 2021 GP is the general partner of the 2021 Partnership, and 2021 LLC is the general partner of 2021 GP. As such, 2021 GP and 2021 LLC may each be deemed to indirectly beneficially own the securities that are directly beneficially owned by the 2021 Partnership.

As of the Event Date, the 2023 Partnership was the direct beneficial owner of 3,200,000 shares of Common Stock described in the second paragraph of this Item 4(a). 2023 GP is the general partner of the 2023 Partnership, and 2023 LLC is the general partner of 2023 GP. As such, 2023 GP and 2023 LLC may each be deemed to indirectly beneficially own the securities that are directly beneficially owned by the 2023 Partnership.

Additionally, as of the Event Date: (i) Alphabet Holdings was the sole managing member of each of 2019 LLC, 2021 LLC, and 2023 LLC; (ii) XXVI was the sole managing member of Alphabet Holdings; and (iii) Parent was the controlling stockholder of XXVI. As such, each of Alphabet Holdings, XXVI, and Parent may be deemed to indirectly beneficially own all of the Issuer’s securities that are directly or indirectly beneficially owned by each of the other Reporting Persons, comprising an aggregate total of 15,062,498 shares of the Issuer’s Common Stock.

Notwithstanding, the filing of this Amendment shall not be construed as an admission by any of the Reporting Persons, for purposes of Sections 13(d) or 13(g) of the Exchange Act or otherwise, as to beneficial ownership of the securities reported in this Amendment.

As of the Event Date, the Reporting Persons were deemed to directly or indirectly beneficially own an aggregate 12.2% of the Issuer’s outstanding Common Stock. Of that percentage, beneficial ownership was attributable as follows: (i) 8.2%, directly to the 2019 Partnership and indirectly to each of 2019 GP and 2019 LLC; (ii) 1.4%, directly to the 2021 Partnership and indirectly to each of 2021 GP and 2021 LLC; (iii) 2.6%, directly to the 2023 Partnership and indirectly to each of 2023 GP and 2023 LLC; and (iv) 12.2%, indirectly to each of Alphabet Holdings, XXVI, and Parent.

The aforementioned percentages were calculated in accordance with Rule 13(d)-3(d)(1)(i) promulgated under the Exchange Act and based on an aggregate total of 123,084,301 shares of the Issuer’s Common Stock outstanding as of the Event Date, as reported by the Issuer in its prospectus supplement (the “Prospectus”) dated February 14, 2024, and filed with the SEC on February 16, 2024, pursuant to Rule 424(b)(5) promulgated under the Securities Act of 1933, as amended, and after giving effect to the full exercise of the underwriters allotment as confirmed by the Issuer in its press release dated February 20, 2024.

(i)       Sole power to vote or to direct the vote:

(ii)       Shared power to vote or to direct the vote:

(iii)       Sole power to dispose or to direct the disposition of:

(iv)       Shared power to dispose or to direct the disposition of:

If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than 5 percent of the class of securities, check the following ¨

Under certain circumstances described more specifically in the respective: (i) limited partnership agreements of the 2019 Partnership, the 2021 Partnership, the 2023 Partnership, 2019 GP, 2021 GP, and 2023 GP and (ii) limited liability company agreements of 2019 LLC, 2021 LLC, and 2023 LLC, the general and limited partners or members, as the case may be, of each of such Reporting Persons may be deemed to have the right to receive dividends from, or proceeds from the sale of, the Issuer’s securities directly or indirectly owned by each Reporting Person of which it is a general partner, limited partner, or member.

Item 7 is not applicable.

Item 8 is not applicable.

Item 9 is not applicable.

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.141-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.