Mirum Pharmaceuticals (MIRM) director converts 3,977 RSUs into 9,680-share holding

Rhea-AI Filing Summary

Director Timothy P. Walbert of Mirum Pharmaceuticals, Inc. exercised previously granted restricted stock units that converted into 3,977 shares of common stock on May 29, 2026. These units represented a contingent right to receive one share of common stock for each unit.

After the transaction, Walbert directly holds 9,680 shares of common stock. The filing shows a routine compensation-related derivative exercise, with no open-market buying or selling and no remaining restricted stock units from this grant.

Insider Trade Summary

3,977 shares exercised/converted

Mixed 2 txns

Insider Walbert Timothy P

Role null

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units	3,977	$0.00	--
Exercise	Common Stock	3,977	$0.00	--

Holdings After Transaction: Restricted Stock Units — 0 shares (Direct, null); Common Stock — 9,680 shares (Direct, null)

Footnotes (1)

1. Each restricted stock unit represents a contingent right to receive one share of common stock (or its cash equivalent, at the discretion of the Issuer). Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock and vests on May 29, 2026.

Key Figures

RSUs exercised: 3,977 units Shares received: 3,977 shares Post-transaction holdings: 9,680 shares +1 more

4 metrics

RSUs exercised 3,977 units Restricted stock units converted on May 29, 2026

Shares received 3,977 shares Common stock issued from RSU conversion

Post-transaction holdings 9,680 shares Common stock directly owned after transaction

Exercise price per unit $0.00 Stated transaction price for RSU conversion

Key Terms

Restricted Stock Units, derivative security, contingent right

3 terms

Restricted Stock Units financial

"The 3,977 restricted stock units vested and were exercised into 3,977 shares"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

derivative security financial

"Transaction code M is described as an exercise or conversion of a derivative security"

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

contingent right financial

"Each restricted stock unit represents a contingent right to receive one share of common stock"

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Form 4 Insider Transactions: What Each Field Means →

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).

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^*

Walbert Timothy P

(Last) (First) (Middle)

C/O MIRUM PHARMACEUTICALS, INC.

989 E HILLSDALE BLVD., SUITE 300

(Street)

FOSTER CITY CALIFORNIA 94404

(City) (State) (Zip)

UNITED STATES

(Country)

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

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

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/29/2026

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

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

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

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	05/29/2026		M		3,977	A	(1)	9,680	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
Restricted Stock Units	(1)	05/29/2026		M			3,977	(2)	(2)	Common Stock	3,977	$0	0	D

Explanation of Responses:

1. Each restricted stock unit represents a contingent right to receive one share of common stock (or its cash equivalent, at the discretion of the Issuer).

2. Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock and vests on May 29, 2026.

	/s/ Judit Ryvkin, Attorney-in-Fact	06/02/2026
	** 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.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did Mirum Pharmaceuticals (MIRM) report for Timothy P. Walbert?

Mirum Pharmaceuticals reported that director Timothy P. Walbert exercised 3,977 restricted stock units into common shares. This was a derivative exercise of equity compensation, not an open-market purchase or sale, and reflects routine vesting rather than a discretionary trade.

How many Mirum Pharmaceuticals (MIRM) shares does Timothy P. Walbert hold after this Form 4?

Following the conversion of restricted stock units, Timothy P. Walbert directly owns 9,680 shares of Mirum Pharmaceuticals common stock. This total reflects the addition of 3,977 shares received from the vested units reported in the Form 4 filing.

What happened to the 3,977 restricted stock units reported by Mirum Pharmaceuticals (MIRM)?

The 3,977 restricted stock units vested and were exercised into 3,977 shares of Mirum Pharmaceuticals common stock. After this conversion, the restricted stock unit balance for this grant is zero, indicating all units under this award have been fully settled in shares.

Were the Mirum Pharmaceuticals (MIRM) insider transactions open-market buys or sells?

The reported transactions were not open-market buys or sells. They were coded as derivative exercises, where restricted stock units converted into common stock at a stated price of $0.00 per unit, typical for equity compensation vesting rather than market trading.

What do the footnotes in the Mirum Pharmaceuticals (MIRM) Form 4 say about the restricted stock units?

The footnotes explain that each restricted stock unit represents a contingent right to receive one share of Mirum common stock or its cash equivalent. They also state that these units vest on May 29, 2026, aligning with the reported conversion date in the filing.