SCHEDULE 13D/A 0001193125-19-204056 0001720320 XXXXXXXX LIVE 7 Common Stock, par value $0.0001 per share 11/01/2025 false 0001759425 604749101 MIRUM PHARMACEUTICALS, INC.

989 E Hillsdale Blvd., Suite 300 FOSTER CITY CA 94404

Steve R. Bailey (206) 621-7200 601 Union Street, Suite 3200 Seattle WA 98101 0001720320 N Frazier Life Sciences IX, L.P. b WC N DE 0.00 3566912.00 0.00 3566912.00 3566912.00 N 7.1 PN The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001782789 N FHMLS IX, L.P. b AF N DE 0.00 3566912.00 0.00 3566912.00 3566912.00 N 7.1 PN The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001782791 N FHMLS IX, L.L.C. b AF N DE 0.00 3566912.00 0.00 3566912.00 3566912.00 N 7.1 OO The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001790879 N Frazier Life Sciences X, L.P. b WC N DE 0.00 168308.00 0.00 168308.00 168308.00 N 0.3 PN The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001790880 N FHMLS X, L.P. b AF N DE 0.00 168308.00 0.00 168308.00 168308.00 N 0.3 PN The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001790811 N FHMLS X, L.L.C. b AF N DE 0.00 168308.00 0.00 168308.00 168308.00 N 0.3 OO The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001863769 N Frazier Life Sciences Public Fund, L.P. b WC N DE 0.00 2514947.00 0.00 2514947.00 2514947.00 N 5.0 PN The shares listed in rows 8, 10 and 11 include shares that were acquired from Frazier Life Sciences Public Overage Fund, L.P. pursuant to a merger between Frazier Life Sciences Public Overage Fund, L.P. and Frazier Life Sciences Public Fund, L.P. The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001879466 N FHMLSP, L.P. b AF N DE 0.00 2514947.00 0.00 2514947.00 2514947.00 N 5.0 PN The shares listed in rows 8, 10 and 11 include shares that were acquired from Frazier Life Sciences Public Overage Fund, L.P. pursuant to a merger between Frazier Life Sciences Public Overage Fund, L.P. and Frazier Life Sciences Public Fund, L.P. The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001879465 N FHMLSP, L.L.C. b AF N DE 0.00 2514947.00 0.00 2514947.00 2514947.00 N 5.0 OO The shares listed in rows 8, 10 and 11 include shares that were acquired from Frazier Life Sciences Public Overage Fund, L.P. pursuant to a merger between Frazier Life Sciences Public Overage Fund, L.P. and Frazier Life Sciences Public Fund, L.P. The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001911592 N Frazier Life Sciences XI, L.P. b WC N DE 0.00 544954.00 0.00 544954.00 544954.00 N 1.1 PN The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001911580 N FHMLS XI, L.P. b AF N DE 0.00 544954.00 0.00 544954.00 544954.00 N 1.1 PN The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001911623 N FHMLS XI, L.L.C. b AF N DE 0.00 544954.00 0.00 544954.00 544954.00 N 1.1 OO The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025. 0001341382 N James N. Topper b AF N X1 0.00 3735220.00 0.00 3735220.00 3735220.00 N 7.4 IN The shares listed in rows 8, 10 and 11 represents (i) 3,566,912 shares of Common Stock held directly by Frazier Life Sciences IX, L.P., and (ii) 163,643 shares of Common Stock held directly by Frazier Life Sciences X, L.P. The percentage listed in row 13 is calculated based on 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025.. 0001365617 N Patrick J. Heron b AF N X1 82482.00 3735220.00 82482.00 3735220.00 3735220.00 N 7.6 IN The shares listed in rows 8, 10 and 11 represents (i) 5,703 shares of Common Stock held directly by the Reporting Person, (ii) 76,779 shares of Common Stock that are issuable upon the exercise of options held directly by the Reporting Person, (iii) 3,566,912 shares of Common Stock held directly by Frazier Life Sciences IX, L.P., and (iv) 163,643 shares of Common Stock held directly by Frazier Life Sciences X, L.P. The percentage listed in row 13 is calculated based on (i) 50,237,647 shares of Common Stock outstanding on August 1, 2025 as set forth in the Issuer's Quarterly Report on Form 10-Q filed with the SEC on August 6, 2025 and (ii) 76,779 shares of Common Stock that are issuable upon the exercise of options held directly by the Reporting Person. Common Stock, par value $0.0001 per share MIRUM PHARMACEUTICALS, INC. 989 E Hillsdale Blvd., Suite 300 FOSTER CITY CA 94404 This Amendment No. 7 ("Amendment No. 7") to Schedule 13D amends the statement on Schedule 13D filed on July 26 2019 (the "Original Schedule 13D") as amended on April 29, 2020, December 18, 2020, August 16, 2022, April 14, 2023, September 5, 2023 and August 20, 2025 (the "Prior Amendments", and together with the Original Schedule 13D and this Amendment No. 7, the "Schedule 13D"). Except as otherwise specified in this Amendment No. 7, all items in the Original Schedule 13D, as amended by the Prior Amendments, are unchanged. All capitalized terms used in this Amendment No. 7 and not otherwise defined herein have the meanings ascribed to such terms in the Original Schedule 13D, as amended by the Prior Amendments. The entities and persons filing this statement (collectively, the "Reporting Persons") are: Frazier Life Sciences IX, L.P. ("FLS IX") FHMLS IX, L.P. FHMLS IX, L.L.C. Frazier Life Sciences X, L.P. ("FLS X") FHMLS X, L.P. FHMLS X, L.L.C. Frazier Life Sciences Public Fund, L.P. ("FLSPF") FHMLSP, L.P. FHMLSP, L.L.C. Frazier Life Sciences XI, L.P. ("FLS XI") FHMLS XI, L.P. FHMLS XI, L.L.C. James N. Topper ("Topper") Patrick J. Heron ("Heron" and together with Topper, the "Members") Item 2(c) is hereby amended and restated in its entirety to read as follows: FLS IX is a venture capital fund concentrating in life sciences and related fields. The sole business of FHMLS IX, L.P. is to serve as general partner of FLS IX. The sole business of FHMLS IX, L.L.C. is to serve as general partner of FHMLS IX, L.P. FLS X is a venture capital fund concentrating in life sciences and related fields. The sole business of FHMLS X, L.P. is to serve as general partner of FLS IX. The sole business of FHMLS X, L.L.C. is to serve as general partner of FHMLS X, L.P. FLSPF is a venture capital fund concentrating in life sciences and related fields. The sole business of FHMLSP, L.P. is to serve as general partner of FLSPF. The sole business of FHMLSP, L.L.C. is to serve as general partner of FHMLSP, L.P. FLS XI is a venture capital fund concentrating in life sciences and related fields. The sole business of FHMLS XI, L.P. is to serve as general partner of FLS XI. The sole business of FHMLS XI, L.L.C. is to serve as general partner of FHMLS XI, L.P. The principal business of the Members is to manage FLS IX, FHMLS IX, L.P., FHMLS IX, L.L.C., FLS X, FHMLS X, L.P., FHMLS X, L.L.C., FLSPF, FHMLSP, L.P., FHMLSP, L.L.C., FLS XI, FHMLS XI, L.P., FHMLS XI, L.L.C. and a number of affiliated partnerships with similar businesses. Item 3 of the Schedule 13D is hereby amended to incorporate Item 5(c) hereof and to replace the last paragraph with the following: The working capital of FLS IX, FLS X, FLSPF and FLS XI was the source of the funds for the purchase of the FLS IX Shares, the FLS X Shares, the FLSPF Shares, and the FLS XI Shares. No part of the purchase price of the FLS IX Shares, the FLS X Shares, the FLSPF Shares, or the FLS XI Shares was represented by funds or other consideration borrowed or otherwise obtained for the purpose of acquiring, holding, trading or voting the FLS IX Shares, the FLS X Shares, the FLSPF Shares and the FLS XI Shares. Item 4 is hereby amended to remove references to "FLSPOF" and the "FLSPOF Shares" from the first paragraph. 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 2,514,947 shares of Common Stock of the Issuer (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.. FLS IX directly holds 3,566,912 shares of Common Stock of the Issuer (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. FLS X directly holds 168,308 shares of Common Stock of the Issuer (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 544,954 shares of Common Stock of the Issuer (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. 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. Except as set forth in Item 6 hereof, none of the Reporting Persons has effected any transactions relating to the Common Stock of the Issuer during the past 60 days. Item 4 is hereby amended to remove references to the "FLSPOF Shares". On November 1, 2025, FLSPF and Frazier Life Sciences Public Overage Fund, L.P. ("FLSPOF") entered into a merger agreement, which resulted in FLSPOF merging with and into FLSPF. As a result of the merger, (i) FLSPF acquired 940,573 shares of Common Stock of the Issuer from FLSPOF and (ii) FLSPOF, FHMLSP Overage, L.P., FHMLSP Overage, L.L.C. ceased being Reporting Persons under the Schedule 13D. Exhibit 99.1 Joint Filing Agreement Frazier Life Sciences IX, L.P. /s/ Steve R. Bailey 11/04/2025 FHMLS IX, L.P. /s/ Steve R. Bailey 11/04/2025 FHMLS IX, L.L.C. /s/ Steve R. Bailey 11/04/2025 Frazier Life Sciences X, L.P. /s/ Steve R. Bailey 11/04/2025 FHMLS X, L.P. /s/ Steve R. Bailey 11/04/2025 FHMLS X, L.L.C. /s/ Steve R. Bailey 11/04/2025 Frazier Life Sciences Public Fund, L.P. /s/ Steve R. Bailey 11/04/2025 FHMLSP, L.P. /s/ Steve R. Bailey 11/04/2025 FHMLSP, L.L.C. /s/ Steve R. Bailey 11/04/2025 Frazier Life Sciences XI, L.P. /s/ Steve R. Bailey 11/04/2025 FHMLS XI, L.P. /s/ Steve R. Bailey 11/04/2025 FHMLS XI, L.L.C. /s/ Steve R. Bailey 11/04/2025 James N. Topper /s/ Steve R. Bailey 11/04/2025 Patrick J. Heron /s/ Steve R. Bailey 11/04/2025