What is the role of the Rule 10b5-1 Plan in Saira Ramasastry’s MIRM share sale?

The Form 4 states the reported sale occurred pursuant to a Rule 10b5-1 Plan adopted on September 18, 2025. Such plans pre-schedule trades, indicating the timing of this 3,977-share sale at $100.0000 was set in advance.

Mirum director sells 3,977 shares at $100

Mirum Pharmaceuticals director Saira Ramasastry reported an exercise-and-sale transaction involving 3,977 shares of common stock.

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Filing Sentiment

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Form Type

Rhea-AI Filing Summary

Mirum Pharmaceuticals director Saira Ramasastry reported an exercise-and-sale transaction involving 3,977 shares of common stock. On May 29, 2026, 3,977 restricted stock units were converted into 3,977 shares of common stock at a stated price of $0.0000 per share. On June 1, 2026, all 3,977 shares were sold in an open-market transaction at $100.0000 per share, leaving 0 shares of common stock reported as directly held after the sale. The filing notes that the sale was carried out under a pre-arranged Rule 10b5-1 trading plan adopted on September 18, 2025, indicating the timing was set in advance.

Insider Trade Summary

Exercise and sale activity reported; no spread calculated

Exercise and Sale 3 txns

Insider Ramasastry Saira

Role Director

Sold 3,977 shs ($398K)

Approx. gross sale proceeds $398K

Approx. exercise cost $0.00

Type	Security	Shares	Price	Value
Sale	Common Stock	3,977	$100.00	$398K
Exercise	Restricted Stock Units	3,977	$0.00	$0.00
Exercise	Common Stock	3,977	$0.00	$0.00

Holdings After Transaction: Restricted Stock Units — 0 contracts (Direct); Common Stock — 0 shares (Direct)

Footnotes (3)

F1. 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).
F2. Reported transaction occurred pursuant to a Rule 10b5-1 Plan adopted by the reporting person on September 18, 2025.
F3. 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

Shares sold: 3,977 shares Sale price per share: $100.0000 per share Shares exercised from RSUs: 3,977 shares +2 more

5 metrics

Shares sold 3,977 shares Common stock sold on June 1, 2026

Sale price per share $100.0000 per share Open-market sale of common stock

Shares exercised from RSUs 3,977 shares RSUs converted to common stock on May 29, 2026

Shares held after transaction 0.0000 shares Total directly held common stock following sale

Net share change -3,977 shares NetBuySellShares from transaction summary

Key Terms

Restricted Stock Units, Rule 10b5-1 Plan, open-market sale, derivative security

4 terms

Restricted Stock Units financial

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

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.

Rule 10b5-1 Plan regulatory

"Reported transaction occurred pursuant to a Rule 10b5-1 Plan adopted by the reporting person"

A Rule 10b5-1 plan is a prearranged, written schedule that lets corporate insiders buy or sell company stock at set times or amounts, even if they later learn material nonpublic information. Think of it like setting an automatic thermostat for trades: it creates a clear record that trades were planned in advance, reducing the risk of insider-trading accusations and helping investors trust that insider transactions are routine rather than based on secret information.

open-market sale financial

"transaction_action": "open-market sale""

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

derivative security financial

"transaction_code_description": "Exercise or conversion of 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.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did Mirum Pharmaceuticals (MIRM) director Saira Ramasastry report in this Form 4?

Director Saira Ramasastry reported exercising 3,977 restricted stock units into common shares, then selling all 3,977 shares. The sale was conducted under a pre-arranged Rule 10b5-1 trading plan adopted on September 18, 2025.

How many Mirum Pharmaceuticals (MIRM) shares did Saira Ramasastry sell and at what price?

She sold 3,977 shares of Mirum Pharmaceuticals common stock at a price of $100.0000 per share. The transaction was classified as an open-market sale and occurred on June 1, 2026, according to the Form 4 data.

What was the sequence of transactions reported by Saira Ramasastry for MIRM?

On May 29, 2026, 3,977 restricted stock units were converted into 3,977 common shares. On June 1, 2026, all 3,977 shares were sold in an open-market transaction under a Rule 10b5-1 trading plan.

Did Saira Ramasastry retain any Mirum Pharmaceuticals (MIRM) shares after these transactions?

After the open-market sale of 3,977 shares, the Form 4 reports total shares of Mirum Pharmaceuticals common stock directly held as 0.0000. This indicates no directly reported common stock holdings remained following the disclosed transactions.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 06/02/2026 - 07:50 PM EDT

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^*

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)
05/29/2026

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	05/29/2026		M		3,977	A	⁽¹⁾	3,977	D
Common Stock	06/01/2026		S⁽²⁾		3,977	D	$100	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Restricted Stock Units	⁽¹⁾	05/29/2026		M			3,977	⁽³⁾	⁽³⁾	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. Reported transaction occurred pursuant to a Rule 10b5-1 Plan adopted by the reporting person on September 18, 2025.

3. 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)

Source: View Original Filing on SEC EDGAR