SCHEDULE 13D/A 0001863769 XXXXXXXX LIVE 10 Common Stock, $0.0001 par value per share 08/18/2025 false 0001783183 71722W107 PHATHOM PHARMACEUTICALS, INC.

100 CAMPUS DRIVE, SUITE 102 FLORHAM PARK NJ 07932

Steve R. Bailey (206) 621-7200 601 Union Street, Suite 3200 Seattle WA 98101 0001863769 N Frazier Life Sciences Public Fund, L.P. b WC N DE 0.00 4234991.00 0.00 4234991.00 4234991.00 N 6.0 PN The Aggregate Amount represents shares held by the Reporting Person and do not include any warrants held by the Reporting Person. See Item 5(a) to this Schedule 13D. The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001879466 N FHMLSP, L.P. b AF N DE 0.00 4234991.00 0.00 4234991.00 4234991.00 N 6.0 PN The Aggregate Amount represents shares held by the Reporting Person and do not include any warrants held by the Reporting Person. See Item 5(a) to this Schedule 13D. The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001879465 N FHMLSP, L.L.C. b AF N DE 0.00 4234991.00 0.00 4234991.00 4234991.00 N 6.0 OO The Aggregate Amount represents shares held by the Reporting Person and do not include any warrants held by the Reporting Person. See Item 5(a) to this Schedule 13D. The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001913804 N Frazier Life Sciences Public Overage Fund, L.P. b WC N DE 0.00 1088365.00 0.00 1088365.00 1088365.00 N 1.6 PN The Aggregate Amount represents shares held by the Reporting Person and do not include any warrants held by the Reporting Person. See Item 5(a) to this Schedule 13D. The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001963247 N FHMLSP Overage, L.P. b AF N DE 0.00 1088365.00 0.00 1088365.00 1088365.00 N 1.6 PN The Aggregate Amount represents shares held by the Reporting Person and do not include any warrants held by the Reporting Person. See Item 5(a) to this Schedule 13D. The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001963248 N FHMLSP Overage, L.L.C. b AF N DE 0.00 1088365.00 0.00 1088365.00 1088365.00 N 1.6 OO The Aggregate Amount represents shares held by the Reporting Person and do not include any warrants held by the Reporting Person. See Item 5(a) to this Schedule 13D. The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001790879 N Frazier Life Sciences X, L.P. b WC N DE 0.00 59403.00 0.00 59403.00 59403.00 N 0.1 PN The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001790880 N FHMLS X, L.P. b AF N DE 0.00 59403.00 0.00 59403.00 59403.00 N 0.1 PN The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001790811 N FHMLS X, L.L.C. b AF N DE 0.00 59403.00 0.00 59403.00 59403.00 N 0.1 OO The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001911592 N Frazier Life Sciences XI, L.P. b WC N DE 0.00 980286.00 0.00 980286.00 980286.00 N 1.4 PN The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001911580 N FHMLS XI, L.P. b AF N DE 0.00 980286.00 0.00 980286.00 980286.00 N 1.4 PN The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001911623 N FHMLS XI, L.L.C. b AF N DE 0.00 980286.00 0.00 980286.00 980286.00 N 1.4 OO The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001720320 N Frazier Life Sciences IX, L.P. b WC N DE 0.00 5827415.00 0.00 5827415.00 5827415.00 N 8.2 PN The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001782789 N FHMLS IX, L.P. b AF N DE 0.00 5827415.00 0.00 5827415.00 5827415.00 N 8.2 PN The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001782791 N FHMLS IX, L.L.C. b AF N DE 0.00 5827416.00 0.00 5827416.00 5827416.00 N 8.2 OO The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0002052255 N Frazier Life Sciences XII, L.P. b WC N DE 0.00 276029.00 0.00 276029.00 276029.00 N 0.4 PN The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0002052246 N FHMLS XII, L.P. b AF N DE 0.00 276029.00 0.00 276029.00 276029.00 N 0.4 PN The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0002052177 N FHMLS XII, L.L.C. b AF N DE 0.00 276029.00 0.00 276029.00 276029.00 N 0.4 OO The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001341382 N James N. Topper b AF N X1 98508.00 5886819.00 98508.00 5886819.00 5985327.00 N 8.6 IN The Aggregate Amount represents (i) 32,096 shares of Common Stock held directly by the Reporting Person, (ii) 3,912 shares of Common Stock held by Topper Group III LLC, (iii) 62,500 shares of Common Stock that are issuable upon the exercise of options held directly by the Reporting Person, (iv) 5,827,415 shares of Common Stock held directly by Frazier Life Sciences IX, L.P., (v) 1 share of Common Stock held directly by FHMLS IX, L.L.C., and (vi) 48,203 shares of Common Stock held directly by Frazier Life Sciences X, L.P. The Aggregate Amount does not include any warrants held by the Reporting Person. See Item 5(a) to this Schedule 13D. The Percent of Class is calculated based on (i) 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. and (ii) 62,500 shares of Common Stock that are issuable upon the exercise of options held directly by the Reporting Person. 0001365617 N Patrick J. Heron b AF N X1 14937.00 5886819.00 14937.00 5886819.00 5901756.00 N 8.4 IN The Aggregate Amount represents (i)14,937 shares of Common Stock held by The Heron Living Trust 11/30/2004, (ii) 5,827,415 shares of Common Stock held directly by Frazier Life Sciences IX, L.P., (iii) 1 share of Common Stock held directly by FHMLS IX, L.L.C., and (iv) 48,203 shares of Common Stock held directly by Frazier Life Sciences X, L.P. The Aggregate Amount does not include any warrants held by the Reporting Person. See Item 5(a) to this Schedule 13D. The Percent of Class is calculated based on 70,943,708 shares of the Issuer's Common Stock outstanding as of August 4, 2025, as reported in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 7, 2025. 0001397906 N Albert Cha b AF N X1 0.00 0.00 0.00 0.00 0.00 N 0.0 IN 0001865123 N James Brush b AF N X1 0.00 0.00 0.00 0.00 0.00 N 0.0 IN 0001702527 N Daniel Estes b AF N X1 0.00 0.00 0.00 0.00 0.00 N 0.0 IN Common Stock, $0.0001 par value per share PHATHOM PHARMACEUTICALS, INC. 100 CAMPUS DRIVE, SUITE 102 FLORHAM PARK NJ 07932 This Amendment No. 10 ("Amendment No. 10") to Schedule 13D amends the statement on Schedule 13D filed on November 6, 2019 (the "Original Schedule 13D"), as amended on June 17, 2020, December 23, 2020, August 11, 2022, September 26, 2022, May 5, 2023, May 26, 2023, June 6, 2024, August 22, 2024 and May 13, 2025 (the "Prior Amendments", and together with the Original Schedule 13D and this Amendment No. 10, the "Schedule 13D"). Except as otherwise specified in Amendment No. 10, all items in the Original Schedule 13D, as amended by the Prior Amendments, are unchanged. All capitalized terms used in this Amendment No. 10 and not otherwise defined herein have the meanings ascribed to such terms in the Original Schedule 13D, as amended by the Prior Amendments. The information contained in Rows 7, 8, 9, 10, 11, and 13 of each Reporting Person's cover page to this Schedule 13D (including the footnotes thereto) is incorporated by reference into this Item 5. FLSPF directly holds 4,234,991 shares of the Issuer's Common Stock (the "FLSPF Shares"). FHMLSP, L.P. is the general partner of FLSPF and the general partner of FHMLSP, L.P. is FHMLSP, L.L.C., which is managed by an investment committee of four that acts by majority vote. Accordingly, no members of such committee are attributed beneficial ownership of the securities directly held by FLSPF, and this Schedule 13D corrects any previous attribution to, and overstatement of beneficial ownership by, such members as reflected in any prior Statements. FLSPOF directly holds 1,088,365 shares of this Issuer's Common Stock (the "FLSPOF Shares"). FHMLSP Overage, L.P. is the general partner of FLSPOF and the general partner of FHMLSP Overage, L.P. is FHMLSP Overage, L.L.C., which is managed by an investment committee of four that acts by majority vote. Accordingly, no members of such committee are attributed beneficial ownership of the securities directly held by FLSPOF, and this Schedule 13D corrects any previous attribution to, and overstatement of beneficial ownership by, such members as reflected in any prior Statements. FLS IX directly holds 5,827,415 shares of the Issuer's Common Stock (the "FLS IX Shares"). FHMLS IX, L.P. is the general partner of FLS IX and FHMLS IX, L.L.C. is the general partner of FHMLS IX, L.P. Heron and Topper are the members of FHMLS IX, L.L.C. and therefore share voting and investment power over the FLS IX Shares. FHMLS IX, L.L.C. directly holds 1 share of the Issuer's Common Stock (the "FHMLS IX, L.L.C. Share"). Heron and Topper are the members of FHMLS IX, L.L.C. and therefore share voting and investment power over the FHMLS IX, L.L.C. Share. FLS X directly holds 59,403 shares of the Issuer's Common Stock (the "FLS X Shares"). FHMLS X, L.P. is the general partner of FLS X and FHMLS X, L.L.C. is the general partner of FHMLS X, L.P. Heron and Topper are the members of FHMLS X, L.L.C. and therefore share voting and investment power over the FLS X Shares. FLS XI directly holds the FLS XI Shares. FHMLS XI, L.P. is the general partner of FLS XI and the general partner of FHMLS XI, L.P. is FHMLS XI, L.L.C., which is managed by an investment committee of three that acts by majority vote. Accordingly, no members of such committee are attributed beneficial ownership of the securities directly held by FLS XI, and this Schedule 13D corrects any previous attribution to, and overstatement of beneficial ownership by, such members as reflected in any prior Statements. FLS XII directly holds FLS XI holds 980,286 shares of this Issuer's Common Stock (the "FLS XI Shares"). FHMLS XII, L.P. is the general partner of FLS XII and the general partner of FHMLS XII, L.P. is FHMLS XII, L.L.C., which is managed by an investment committee of three that acts by majority vote. Accordingly, no members of such committee are attributed beneficial ownership of the securities directly held by FLS XII, and this Schedule 13D corrects any previous attribution to, and overstatement of beneficial ownership by, such members as reflected in any prior Statements. The above referenced beneficial ownership and amounts reflected on the cover pages hereto do not include certain warrants and prefunded warrants to acquire shares of Common Stock (the "Warrants"), the exercise of which is subject to certain beneficial ownership limitations. In this regard, (i) FLSPF holds Warrants to purchase 2,004,956 shares of Common Stock, (ii) FLSPOF holds Warrants to purchase 591,443 shares of Common Stock, and (iii) FLS XII holds Warrants to purchase 12,523 shares of Common Stock, each of which cannot be exercised, if, upon giving effect to such exercise, the aggregate number of shares of Common Stock beneficially owned by the holder of such Warrant (together with its affiliates or any other persons acting as a group together with such holder) would exceed 19.99% of the number of shares of Common Stock outstanding immediately after giving effect to such exercise. Except as specifically stated herein, the filing of this Schedule 13D shall not be construed as an admission that any Reporting Person or any of the foregoing is, for the purposes of Section 13(d) and/or Section 13(g) of the Act or otherwise, the beneficial owner of any securities covered by this Schedule 13D or a member of a "group" with any other person. EX-99.1 Joint Filing Agreement, dated as of May 13, 2025, incorporated by reference into this Schedule 13D. Frazier Life Sciences Public Fund, L.P. /s/ Steve R. Bailey 08/20/2025 FHMLSP, L.P. /s/ Steve R. Bailey 08/20/2025 FHMLSP, L.L.C. /s/ Steve R. Bailey 08/20/2025 Frazier Life Sciences Public Overage Fund, L.P. /s/ Steve R. Bailey 08/20/2025 FHMLSP Overage, L.P. /s/ Steve R. Bailey 08/20/2025 FHMLSP Overage, L.L.C. /s/ Steve R. Bailey 08/20/2025 Frazier Life Sciences X, L.P. /s/ Steve R. Bailey 08/20/2025 FHMLS X, L.P. /s/ Steve R. Bailey 08/20/2025 FHMLS X, L.L.C. /s/ Steve R. Bailey 08/20/2025 Frazier Life Sciences XI, L.P. /s/ Steve R. Bailey 08/20/2025 FHMLS XI, L.P. /s/ Steve R. Bailey 08/20/2025 FHMLS XI, L.L.C. /s/ Steve R. Bailey 08/20/2025 Frazier Life Sciences IX, L.P. /s/ Steve R. Bailey 08/20/2025 FHMLS IX, L.P. /s/ Steve R. Bailey 08/20/2025 FHMLS IX, L.L.C. /s/ Steve R. Bailey 08/14/2025 Frazier Life Sciences XII, L.P. /s/ Gordon Empey 08/20/2025 FHMLS XII, L.P. /s/ Gordon Empey 08/20/2025 FHMLS XII, L.L.C. /s/ Gordon Empey 08/20/2025 James N. Topper /s/ Steve R. Bailey 08/20/2025 Patrick J. Heron /s/ Steve R. Bailey 08/20/2025 Albert Cha /s/ Steve R. Bailey 08/20/2025 James Brush /s/ Steve R. Bailey 08/20/2025 Daniel Estes /s/ Steve R. Bailey 08/20/2025