| Item 1. | |
| (a) | Name of issuer:
Septerna, Inc. |
| (b) | Address of issuer's principal executive offices:
250 East Grand AvenueSouth San Francisco, CA 94080 |
| Item 2. | |
| (a) | Name of person filing:
(i) Third Rock Ventures V, L.P. ("TRV V");
(ii) Third Rock Ventures GP V, L.P. ("TRV GP V"), which is the sole general partner of TRV V;
(iii) TRV GP V, LLC ("TRV GP V LLC"), which is the sole general partner of TRV GP V;
(iv) Third Rock Ventures VI, L.P. ("TRV VI");
(v) Third Rock Ventures GP VI, L.P. ("TRV GP VI"), which is the sole general partner of TRV VI; and
(vi) TRV GP VI, LLC ("TRV GP VI LLC"), which is the sole general partner of TRV GP VI. |
| (b) | Address or principal business office or, if none, residence:
The address of the principal business office of each of the Reporting Persons is Third Rock Ventures, LLC, 201 Brookline Ave, Suite 1401, Boston, MA 02215. |
| (c) | Citizenship:
Each of TRV V, TRV GP V, TRV VI and TRV GP VI is a Delaware limited partnership.Each of TRV GP V LLC and TRV GP VI LLC is a Delaware limited liability company. |
| (d) | Title of class of securities:
Common Stock, $0.001 par value per share |
| (e) | CUSIP No.:
81734D104 |
| Item 3. | If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a: |
| (a) |  Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
|
| (b) | Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
|
| (c) | Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
|
| (d) | Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
|
| (e) | An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
|
| (f) | An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
|
| (g) | A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
|
| (h) | A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
|
| (i) | A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
|
| (j) | A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J),
please specify the type of institution:
|
| (k) | Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
|
| | |
| Item 4. | Ownership |
| (a) | Amount beneficially owned:
(i) TRV V directly owns 6,215,591 shares of Common Stock (the "V Shares")
(ii) TRV GP V is the general partner of TRV V and may be deemed to beneficially own the V Shares.
(iii) TRV GP V LLC is the general partner of TRV GP V and may be deemed to beneficially own the V Shares.
(iv) TRV VI directly owns 3,152,456 shares of Common Stock (the "VI Shares").
(v) TRV GP VI is the general partner of TRV VI and may be deemed to beneficially own the VI Shares.
(vi) TRV GP VI LLC is the general partner of TRV GP VI and may be deemed to beneficially own the VI Shares.
Each of TRV V, TRV GP V, and TRV GP V LLC, on the one hand, and TRV VI, TRV GP VI and TRV GP VI LLC, on the other hand, disclaim the existence of a "group" for purposes of Rule 13d-5 of the Securities Exchange Act of 1934, as amended, and nothing contained in this report shall be deemed an admission that any such group exists or may exist. |
| (b) | Percent of class:
The V shares represent approximately 14.0% of the outstanding shares of Common Stock.The VI shares represent approximately 7.1% of the outstanding shares of Common Stock.The percent of class was calculated based on 44,402,742 shares of common stock issued and outstanding as of November 11, 2024, as disclosed in the Issuer's 10-Q filed with the Securities and Exchange Commission on November 20, 2024. |
| (c) | Number of shares as to which the person has:
|
| | (i) Sole power to vote or to direct the vote:
TRV V - 0
TRV GP V - 0
TRV GP V LLC - 0
TRV VI - 0
TRV GP VI - 0
TRV GP VI LLC - 0
|
| | (ii) Shared power to vote or to direct the vote:
TRV V - 6,215,591 shares
TRV GP V - 6,215,591 shares
TRV GP V LLC - 6,215,591 shares
TRV VI - 3,152,456 shares
TRV GP VI - 3,152,456 shares
TRV GP VI LLC - 3,152,456 shares
|
| | (iii) Sole power to dispose or to direct the disposition of:
TRV V - 0
TRV GP V - 0
TRV GP V LLC - 0
TRV VI - 0
TRV GP VI - 0
TRV GP VI LLC - 0
|
| | (iv) Shared power to dispose or to direct the disposition of:
TRV V - 6,215,591 shares
TRV GP V - 6,215,591 shares
TRV GP V LLC - 6,215,591 shares
TRV VI - 3,152,456 shares
TRV GP VI - 3,152,456 shares
TRV GP VI LLC - 3,152,456 shares
|
| Item 5. | Ownership of 5 Percent or Less of a Class. |
| | |
| Item 6. | Ownership of more than 5 Percent on Behalf of Another Person. |
| |
Not Applicable
|
| Item 7. | Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person. |
| |
Not Applicable
|
| Item 8. | Identification and Classification of Members of the Group. |
| |
Not Applicable
|
| Item 9. | Notice of Dissolution of Group. |
| |
Not Applicable
|
Rule 13d-1(d)