[Form 4] Mirum Pharmaceuticals, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Jolanda Howe, SVP, Global Controller of Mirum Pharmaceuticals (MIRM), reported both non-derivative and derivative transactions affecting her holdings. The filing shows a sale of 10,000 common shares at $58.00, after which her reported direct beneficial ownership stood at 2,426 shares. On the same date she recorded an acquisition-related entry at a $6.27 price for 10,000 common shares, with a reported beneficial ownership figure of 12,426 shares following that transaction.

An employee stock option with a conversion/exercise price of $6.27 covering 10,000 underlying shares is reported and is stated to be fully vested. The filing notes the sale was executed pursuant to a Rule 10b5-1 plan adopted December 16, 2024, and the reporting person is shown as beneficial owner of 40,000 derivative securities following the reported activity.

Positive

• Transactions executed under a Rule 10b5-1 plan, indicating pre-arranged trading instructions
• Employee stock option is fully vested, covering 10,000 underlying shares

Negative

• Sale of 10,000 shares at $58.00 reduced direct beneficial ownership to 2,426 shares
• Direct holdings now modest (reported direct ownership of 2,426 shares) after the reported disposition

Insights

Financial Analyst

TL;DR: Insider exercised vested options and executed a 10b5-1 sale; direct holdings fell while derivative exposure remains sizable.

The report shows two principal actions: a disposition of 10,000 common shares at $58.00 and acquisition-related activity tied to a $6.27 price for 10,000 shares. The filing also documents a fully vested employee stock option covering 10,000 underlying shares and indicates 40,000 derivative securities are beneficially owned after the activity. Because the sale was executed under a documented Rule 10b5-1 plan, the transactions reflect pre-arranged activity rather than an ad hoc market sale. For investors, the net change alters direct ownership levels but leaves meaningful derivative exposure.

Corporate Governance Expert

TL;DR: Transactions were carried out under a 10b5-1 plan and involve a fully vested option, indicating planned execution and vested equity compensation.

The Form 4 discloses that the reporting person executed transactions pursuant to a Rule 10b5-1 plan adopted December 16, 2024, and that an employee stock option is fully vested. Those facts are relevant for governance and disclosure: the 10b5-1 plan provides an affirmative defense for trades made under the plan, and vesting status clarifies the reporting person’s ability to exercise or transfer option-derived shares. The filing is procedural and compliant in nature; it documents planned insider activity rather than new corporate events.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a 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). See Instruction 10.

1. Name and Address of Reporting Person^*

Howe Jolanda

(Last) (First) (Middle)

C/O MIRUM PHARMACEUTICALS, INC.

989 E HILLSDALE BLVD., SUITE 300

(Street)

FOSTER CITY CA 94404

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Mirum Pharmaceuticals, Inc. [ MIRM ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	SVP, GLOBAL CONTROLLER

3. Date of Earliest Transaction (Month/Day/Year)
08/07/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/07/2025		M		10,000	A	$6.27	12,426	D
Common Stock	08/07/2025		S(1)		10,000	D	$58	2,426	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Employee Stock Option (right to buy)	$6.27	08/07/2025		M			10,000	(2)	05/13/2029	Common Stock	10,000	$0	40,000	D

Explanation of Responses:

1. Reported transaction occurred pursuant to a Rule 10b5-1 Plan adopted by the reporting person on December 16, 2024.

2. The stock option is fully vested.

	/s/ Judit Ryvkin, Attorney-in-Fact	08/08/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
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FAQ

What insider activity did Mirum (MIRM) report on this Form 4?

The Form 4 reports a sale of 10,000 common shares at $58.00 and acquisition-related activity for 10,000 shares at $6.27, plus derivative reporting.

Who is the reporting person on the Form 4 for MIRM?

The reporting person is Jolanda Howe, listed as SVP, Global Controller of Mirum Pharmaceuticals.

When were the reported transactions executed?

The transactions are reported with a transaction date of 08/07/2025.

Were the trades part of a trading plan?

Yes. The filing states the sale occurred pursuant to a Rule 10b5-1 plan adopted on December 16, 2024.

How many derivative securities does the reporting person beneficially own after the transactions?

The filing shows 40,000 derivative securities beneficially owned following the reported transactions.

Is the reported stock option vested?

Yes. The Form 4 explicitly states the stock option is fully vested.