[144] Mirum Pharmaceuticals, Inc. SEC Filing

Rhea-AI Filing Summary

Mirum Pharmaceuticals reported a Form 144 notice showing a proposed sale of 17,000 common shares to be executed through Morgan Stanley Smith Barney on 09/11/2025. The filing lists an aggregate market value of $1,264,917.30 for the shares against 50,237,647 shares outstanding. The shares were acquired and are being sold on 09/11/2025 as the result of a stock option exercise with payment in cash. The filer certifies they are not aware of undisclosed material adverse information about the issuer. The notice reports no other sales in the past three months.

Positive

• Full disclosure provided via Form 144 including broker, share count, and aggregate market value
• Shares acquired by exercise and sold same day, which clarifies the nature of the transaction and payment (cash)
• No other sales in past three months reported, limiting concerns about concentrated recent insider selling

Negative

• Insider sale of $1.26M could be perceived negatively by some investors despite small relative size
• Filing does not specify whether the sale is part of a Rule 10b5-1 trading plan or the identity of the selling person

Insights

Securities Analyst

TL;DR Insider intends to sell 17,000 shares following an option exercise; not obviously material to company valuation given outstanding share count.

The Form 144 documents a planned sale of 17,000 common shares with an aggregate market value of $1,264,917.30 executed via Morgan Stanley Smith Barney on 09/11/2025. The timing indicates the shares were acquired by exercise and immediately slated for sale, with cash payment. As reported, there were no other insider sales in the prior three months. Relative to 50,237,647 shares outstanding, the position size equals roughly 0.034% of outstanding shares, suggesting limited market impact. The filing contains the required representation that the seller is not aware of undisclosed material adverse information.

Corporate Governance Expert

TL;DR Transaction appears routine: option exercise followed by open-market sale; disclosure complies with Rule 144 requirements.

The notice shows acquisition by stock option exercise and contemporaneous sale via a broker, typical for insiders monetizing equity. The filer affirms no undisclosed material information. No other sales in the past three months are reported, and the filing includes standard signatures and warnings. From a governance perspective, the form fulfills disclosure obligations under Rule 144 but provides no further detail on holder identity or trading plan adoption dates.

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK
Filer CCC
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer

SEC File Number

Address of Issuer

Phone

Name of Person for Whose Account the Securities are To Be Sold

See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.

Relationship to Issuer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	17000	1264917.30	50237647	09/11/2025	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	09/11/2025	Stock Option Exercise	Issuer			17000	09/11/2025	Cash

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Nothing to Report

144: Remarks and Signature

Remarks

Date of Notice

ATTENTION:

The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.

Signature

ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)

FAQ

What does Mirum Pharmaceuticals' (MIRM) Form 144 filed for 09/11/2025 disclose?

The filing discloses a proposed sale of 17,000 common shares through Morgan Stanley Smith Barney on 09/11/2025 with an aggregate market value of $1,264,917.30.

How were the 17,000 shares acquired according to the Form 144?

The shares were acquired on 09/11/2025 by stock option exercise from the issuer, with payment in cash.

Does the Form 144 report any other insider sales in the past three months for MIRM?

No. The filing states Nothing to Report for securities sold during the past three months.

How significant is the proposed sale relative to Mirum's outstanding shares?

The 17,000 shares represent approximately 0.034% of the reported 50,237,647 shares outstanding, a small proportion of the float.

Does the filer assert knowledge of undisclosed material information about Mirum?

Yes. By signing, the filer represents they do not know any material adverse information