MICHAEL G. GREY - 19 Dec 2025 Form 4 Insider Report for Mirum Pharmaceuticals, Inc. (MIRM)

Role
Director
Signature
/s/ Jody Howe, Attorney-in-Fact
Issuer symbol
MIRM
Transactions as of
19 Dec 2025
Net transactions value
-$3,753,200
Form type
4
Filing time
23 Dec 2025, 18:50:04 UTC
Previous filing
15 Dec 2025

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
GREY MICHAEL G Director C/O MIRUM PHARMACEUTICALS, INC., 989 E HILLSDALE BLVD., SUITE 300, FOSTER CITY /s/ Jody Howe, Attorney-in-Fact 23 Dec 2025 0001240122

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
transaction MIRM Common Stock Options Exercise $146,800 +50,000 $2.94 50,000 19 Dec 2025 Direct
transaction MIRM Common Stock Sale $3,900,000 -50,000 -100% $78.00 0 19 Dec 2025 Direct F1
holding MIRM Common Stock 186,410 19 Dec 2025 By The Grey Family Trust dated November 12,1999
holding MIRM Common Stock 93,750 19 Dec 2025 By The Grey 2018 Irrevocable Children's Trust

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
transaction MIRM Stock Option (right to buy) Options Exercise $0 -50,000 -22% $0.000000 181,176 19 Dec 2025 Common Stock 50,000 $2.94 Direct F2
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Buy Plan / Sale Plan: These are also open market purchases/sales of shares, but in this case the transaction is part of a trading plan. Rule 10b5-1 allows insiders to setup a trading plan to buy/sell stocks over a certain period of time. Since the purchases/sales are predetermined, this protects the insiders from violating insider trading law.

Transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c).

Explanation of Responses:

Id Content
F1 Reported transaction occurred pursuant to a Rule 10b5-1 Plan adopted August 22, 2025.
F2 The stock option is fully vested and exercisable.