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

Rhea-AI Filing Summary

Mirum Pharmaceuticals director Saira Ramasastry exercised stock options and sold the resulting shares. On March 16, 2026, she exercised options for 2,000 shares of common stock at an exercise price of $23.51 per share, then sold 2,000 shares in an open‑market transaction at $90.76 per share.

The filing shows she no longer directly holds these 2,000 common shares after the sale. The transactions were carried out under a pre‑arranged Rule 10b5‑1 trading plan adopted on September 18, 2025, indicating they were scheduled in advance rather than timed discretionarily.

Insights

Equity compensation and insider trading analyst

Routine option exercise followed by a pre‑planned sale of 2,000 shares.

Director Saira Ramasastry exercised options to acquire 2,000 Mirum Pharmaceuticals common shares at an exercise price of $23.51 per share, then sold the same 2,000 shares at $90.76 per share. This is a classic exercise‑and‑sell pattern.

The filing indicates these transactions occurred under a Rule 10b5‑1 plan adopted on September 18, 2025, suggesting they were pre‑scheduled. Following the sale, she reports no remaining holdings of these 2,000 common shares. With no remaining derivative positions listed, this appears to complete the reported option position.

Because the transactions are pre‑planned and the share count is modest in isolation, they typically carry limited informational value about the director's current view of the stock. Future company filings may provide broader context on overall insider ownership trends at Mirum Pharmaceuticals.

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

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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 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)

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

3. Date of Earliest Transaction (Month/Day/Year)
03/16/2026

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	03/16/2026		M		2,000	A	$23.51	2,000	D
Common Stock	03/16/2026		S(1)		2,000	D	$90.76	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	03/16/2026		M			2,000	(2)	06/01/2032	Common Stock	2,000	$0	4,000	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	03/17/2026
	** 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.
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FAQ

What insider transactions did Mirum Pharmaceuticals (MIRM) director Saira Ramasastry report?

Director Saira Ramasastry reported exercising stock options for 2,000 Mirum Pharmaceuticals shares at an exercise price of $23.51, then selling 2,000 common shares at $90.76. The filing shows she no longer directly holds these 2,000 common shares after the reported transactions.

Was the Mirum Pharmaceuticals (MIRM) insider trade by Saira Ramasastry a buy or sell?

The activity combined an acquisition and a sale. Ramasastry first acquired 2,000 Mirum shares by exercising stock options, then sold 2,000 common shares in an open‑market transaction at $90.76 per share, resulting in no directly held shares from this block afterward.

What prices were involved in Saira Ramasastry’s Mirum Pharmaceuticals (MIRM) Form 4 transactions?

The option exercise was priced at $23.51 per share, reflecting the stock option exercise price, while the subsequent sale of 2,000 Mirum common shares occurred at $90.76 per share. These figures show a substantial spread between the option strike and the sale price realized.

When did Saira Ramasastry execute her Mirum Pharmaceuticals (MIRM) option exercise and share sale?

Both the option exercise and the sale took place on March 16, 2026. The Form 4 indicates the stock options were exercised that day and the resulting 2,000 common shares were sold the same day in an open‑market transaction at $90.76 per share.

Were Saira Ramasastry’s Mirum Pharmaceuticals (MIRM) trades made under a Rule 10b5-1 plan?

Yes. A footnote states the reported transaction occurred pursuant to a Rule 10b5‑1 plan adopted by Ramasastry on September 18, 2025. Such plans are pre‑arranged trading programs, indicating the timing of this exercise‑and‑sale sequence was scheduled in advance.

How many Mirum Pharmaceuticals (MIRM) shares does Saira Ramasastry hold after these transactions?

For the 2,000 Mirum common shares involved, the Form 4 reports total shares following the sale as zero, meaning she no longer directly holds this specific block. The filing does not list any remaining derivative positions associated with these exercised options.