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

Rhea-AI Filing Summary

Mirum Pharmaceuticals, Inc. director Saira Ramasastry reported an exercise-and-sell transaction in company stock. On May 15, 2026, she exercised stock options to acquire 2,000 shares of common stock at $23.51 per share, then sold 2,000 shares in an open-market transaction at $109.47 per share. The filing shows these trades were executed under a pre-arranged Rule 10b5-1 trading plan adopted on September 18, 2025, indicating they were scheduled in advance. After these transactions, her reported direct common stock holdings were 0 shares, and the exercised option covering 2,000 shares is fully vested and fully exercised.

Insights

Equity compensation and insider-trading analyst

Pre-planned option exercise and full same-day sale, net neutral signal.

Director Saira Ramasastry exercised stock options for 2,000 shares of Mirum Pharmaceuticals common stock at an exercise price of $23.51 per share, then sold the same number of shares at $109.47 per share on May 15, 2026. The derivative entry shows the option, expiring on June 1, 2032, was fully exercised.

The filing notes the transactions occurred under a Rule 10b5-1 Plan adopted on September 18, 2025, meaning the timing was pre-scheduled rather than discretionary. After the sale, reported direct common stock holdings were 0 shares, and no remaining derivative positions are listed, suggesting this was a complete exercise-and-sell of that option grant.

Insider Trade Summary 10b5-1

Net Seller: 2,000 shares ($218,940)

Net Sell 3 txns

Insider Ramasastry Saira

Role null

Sold 2,000 shs ($219K)

Type	Security	Shares	Price	Value
Exercise	Stock Option (right to buy)	2,000	$0.00	--
Exercise	Common Stock	2,000	$23.51	$47K
Sale	Common Stock	2,000	$109.47	$219K

Holdings After Transaction: Stock Option (right to buy) — 0 shares (Direct, null); Common Stock — 2,000 shares (Direct, null)

Footnotes (1)

1. Reported transaction occurred pursuant to a Rule 10b5-1 Plan adopted by the reporting person on September 18, 2025. The stock option is fully vested.

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).

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^*

Ramasastry Saira

(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)
05/15/2026

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	05/15/2026		M		2,000	A	$23.51	2,000	D
Common Stock	05/15/2026		S(1)		2,000	D	$109.47	0	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
Stock Option (right to buy)	$23.51	05/15/2026		M			2,000	(2)	06/01/2032	Common Stock	2,000	$0	0	D

Explanation of Responses:

1. Reported transaction occurred pursuant to a Rule 10b5-1 Plan adopted by the reporting person on September 18, 2025.

2. The stock option is fully vested.

	/s/ Judit Ryvkin, Attorney-in-Fact	05/18/2026
	** 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).
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* Form 4: SEC 1474 (03-26)