BAKER BROS. ADVISORS LP - 12 Feb 2025 Form 3 Insider Report for SERA PROGNOSTICS, INC. (SERA)

Footnote F1

As a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, L.P. ("667") Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in Class A common stock ("Common Stock") of Sera Prognostics, Inc. (the "Issuer") reported in column 2 of Table I and securities of the Issuer reported in column 3 of Table II held directly by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

Footnote F2

Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667 and Baker Brothers Life Sciences, L.P. ("Life Sciences" and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held directly by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held directly by the Funds or for the benefit of the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held directly by the Funds.

Footnote F3

Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

Footnote F4

As a result of their ownership interest in (i) Baker Brothers Life Sciences Capital, L.P. and (ii) Life Sciences, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in Common Stock reported in column 2 of Table I and the securities of the Issuer reported in column 3 of Table II held directly by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

Footnote F5

These securities consist of Class B non-voting common stock of the Issuer ("Class B Common Stock") which are convertible at any time on a 1-for-1 basis without payment or further consideration into Common Stock, subject to a 4.99% beneficial ownership limitation described below. The Class B Common Stock is only convertible to the extent that immediately prior to or as a result of such conversion the holders thereof together with their affiliates and any persons who are members of a Section 13(d) group with the holders or their affiliates would beneficially own in the aggregate, for purposes of Rule 13d-3 under the Exchange Act, no more than 4.99% of the outstanding Common Stock after conversion (the "Class B Beneficial Ownership Limitation"). The Class B Common Stock has no expiration date.

Footnote F6

By written notice to the Issuer, the Funds may increase or decrease the Class B Beneficial Ownership Limitation applicable to that fund to any other percentage not in excess of 19.99%; provided that any such increase will not be effective until the 61st day after such notice is delivered to the Issuer.

Footnote F7

These securities consist of warrants to purchase Common Stock at an exercise price of $0.0001 per share with no expiration date ("Pre-Funded Warrants").

Footnote F8

The Pre-Funded Warrants are exercisable at any time, at the holder's election, on a 1-for-1 basis into Common Stock to the extent that immediately prior to or after giving effect to such exercise the holders thereof, together with their affiliates and any members of a Section 13(d) group with such holders, would beneficially own, for purposes of Rule 13d-3under the Securities Act of 1934, as amended, no more than 4.99% of the outstanding shares of Common Stock (the "Maximum Percentage").

Footnote F9

By written notice to the Issuer, the Funds may increase or decrease the Maximum Percentage applicable to that fund to any other percentage not in excess of 19.99%; provided that any such increase will not be effective until the 61st day after such notice is delivered to the Issuer.