X0306 4 2021-09-29 0 0001759425 Mirum Pharmaceuticals, Inc. MIRM 0001614740 Peetz Christopher C/O MIRUM PHARMACEUTICALS, INC. 950 TOWER LANE, SUITE 1050 FOSTER CITY CA 94404 1 1 0 0 President and CEO Common Stock 2021-09-29 4 A 0 21875 0.00 A 24699 D Common Stock 2021-10-01 4 S 0 3672 19.256 D 21027 D Common Stock 201570 I By The Peetz Family Trust The shares became issuable upon the satisfaction of certain performance conditions that were established at the time of the Compensation Committee's approval of a performance-based restricted stock unit award on March 9, 2021. On September 29, 2021, the Compensation Committee certified the achievement of the performance criteria resulting in the vesting of 10,937 shares on September 29, 2021 and 10,938 shares on June 30, 2023. Shares sold to cover tax withholding obligations associated with the vesting of the performance-based restricted stock unit award granted to the Reporting Person on March 9, 2021. /s/ Jody Howe, Attorney-in-Fact 2021-10-01