[SCHEDULE 13G/A] Mirum Pharmaceuticals, Inc. SEC Filing

Rhea-AI Filing Summary

Janus Henderson Group plc reports beneficial ownership of Mirum Pharmaceuticals common stock totaling 5,236,277 shares, representing approximately 10.6% of the outstanding class. The filing shows the reporting entity holds no sole voting or dispositive power and reports shared voting and dispositive power over the stake. A listed subsidiary, JHIUS, is reported as beneficial owner of 5,140,740 shares (about 10.4%) with shared voting and dispositive authority. The filer certifies these securities are held in the ordinary course of business and not to change control of the issuer.

Positive

• Material disclosure: Reporting of a >5% stake (5,236,277 shares, ~10.6%) provides transparency to the market
• Clear voting profile: Filing specifies shared voting and dispositive power rather than undisclosed control
• Ordinary-course certification: Filer explicitly states holdings are in the ordinary course of business

Negative

• No sole control: The filer reports 0 sole voting and dispositive power, indicating no unilateral governance authority
• Apparent numerical inconsistency: Aggregate reported by the filing (5,236,277 shares, 10.6%) differs from the subsidiary-specific amount (5,140,740 shares, 10.4%) shown in Item 4

Insights

Securities Analyst

TL;DR: Janus Henderson discloses a consequential >10% ownership in Mirum, held with shared voting power, flagged as ordinary-course holdings.

The reported stake exceeds the 5% disclosure threshold and is material to shareholder composition. The stake is held without sole voting or dispositive authority which suggests coordinated management across funds or subsidiaries rather than direct control. This type of institutional position can influence market liquidity and signals institutional interest, but the filing explicitly states it is not intended to change or influence control.

Corporate Governance Expert

TL;DR: A >10% institutional holding is material for governance monitoring but appears passive based on shared powers.

The absence of sole voting or dispositive power indicates Janus Henderson is not asserting unilateral governance control. Investors and the board should note the size of the position for potential engagement or voting coordination during corporate actions. The disclosure also names indirect subsidiaries involved in advisory roles, consistent with multi-entity asset management structures.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 5)

MIRUM PHARAMACEUTICALS, INC.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

604749101

(CUSIP Number)

06/30/2025

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13G

CUSIP No. 604749101

1

Names of Reporting Persons

JANUS HENDERSON GROUP PLC

2

Check the appropriate box if a member of a Group (see instructions)

(a)
(b)

3

Sec Use Only

4

Citizenship or Place of Organization

JERSEY

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 5,236,277.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 5,236,277.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

5,236,277.00

10

Check box if the aggregate amount in row (9) excludes certain shares (See Instructions)

11

Percent of class represented by amount in row (9)

10.6 %

12

Type of Reporting Person (See Instructions)

IA, HC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: MIRUM PHARAMACEUTICALS, INC.
(b)	Address of issuer's principal executive offices: 989 EAST HILLSDALE BOULEVARD, SUITE 300 FOSTER CITY, CA 94404
Item 2.
(a)	Name of person filing: Janus Henderson Group plc
(b)	Address or principal business office or, if none, residence: 201 Bishopsgate EC2M 3AE, United Kingdom
(c)	Citizenship: Y9
(d)	Title of class of securities: Common Stock
(e)	CUSIP No.: 604749101
Item 3.	If this statement is filed pursuant to §§ 240.13d-1(b) or 240.13d-2(b) or (c), check whether the person filing is a:
(a)	Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o);
(b)	Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c);
(c)	Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c);
(d)	Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C. 80a-8);
(e)	An investment adviser in accordance with § 240.13d-1(b)(1)(ii)(E);
(f)	An employee benefit plan or endowment fund in accordance with § 240.13d-1(b)(1)(ii)(F);
(g)	A parent holding company or control person in accordance with § 240.13d-1(b)(1)(ii)(G);
(h)	A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act (12 U.S.C. 1813);
(i)	A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j)	A non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J). If filing as a non-U.S. institution in accordance with § 240.13d-1(b)(1)(ii)(J), please specify the type of institution:
(k)	Group, in accordance with Rule 240.13d-1(b)(1)(ii)(K).
Item 4.	Ownership
(a)	Amount beneficially owned: JHIUS may be deemed to be the beneficial owner of 5,140,740 shares
(b)	Percent of class: 10.4 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: 0
	(ii) Shared power to vote or to direct the vote: 5140740
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 5140740
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	If any other person is known to have the right to receive or the power to direct the receipt of dividends from, or the proceeds from the sale of, such securities, a statement to that effect should be included in response to this item and, if such interest relates to more than 5 percent of the class, such person should be identified. A listing of the shareholders of an investment company registered under the Investment Company Act of 1940 or the beneficiaries of employee benefit plan, pension fund or endowment fund is not required. N/A
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	If a parent holding company has filed this schedule, pursuant to Rule 13d-1(b)(ii)(G), so indicate under Item 3(g) and attach an exhibit stating the identity and the Item 3 classification of the relevant subsidiary. If a parent holding company has filed this schedule pursuant to Rule 13d-1(c) or Rule 13d-1(d), attach an exhibit stating the identification of the relevant subsidiary. JHIUS, JHIUKL and JHIAIFML are indirect subsidiaries of Janus Henderson and are registered investment advisers furnishing investment advice to Managed Portfolios.
Item 8.	Identification and Classification of Members of the Group.
	If a group has filed this schedule pursuant to §240.13d-1(b)(1)(ii)(J), so indicate under Item 3(j) and attach an exhibit stating the identity and Item 3 classification of each member of the group. If a group has filed this schedule pursuant to §240.13d-1(c) or §240.13d-1(d), attach an exhibit stating the identity of each member of the group. N/A
Item 9.	Notice of Dissolution of Group.
	Notice of dissolution of a group may be furnished as an exhibit stating the date of the dissolution and that all further filings with respect to transactions in the security reported on will be filed, if required, by members of the group, in their individual capacity. See Item 5. N/A

Item 10.

Certifications:

By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under § 240.14a-11.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.

JANUS HENDERSON GROUP PLC

Signature:	Kristin Mariani
Name/Title:	Head of North America Compliance, CCO
Date:	08/14/2025

Exhibit Information

POWER OF ATTORNEY The undersigned, Janus Henderson Group plc ("the Company"), does hereby make, constitute and appoint each of Kristin Mariani and Caroline Barotti acting severally, as its true and lawful attorneys in-fact, for the purpose of, from time to time, executing in its name and on its behalf, whether the Company individually or as representative of others, any and all documents, certificates, instruments, statements, other filings and amendments to the foregoing (collectively, "documents") determined by such person to be necessary or appropriate to comply with ownership or control-person reporting requirements imposed by any United States or non-United States governmental or regulatory authority, including, without limitation, Forms 13D, 13F, 13G and 13H and any amendments to any of the foregoing as may be required to be filed with the Securities and Exchange Commission, and delivering, furnishing or filing any such documents with the appropriate governmental, regulatory authority or other person, and giving and granting to each such attorney-in-fact power and authority to act in the premises as fully and to all intents and purposes as the Company might or could do if personally present by one of its authorized signatories, hereby ratifying and confirming all that said attorney-in-fact shall lawfully do or cause to be done by virtue hereof. Any such determination by an attorney-in-fact named herein shall be conclusively evidenced by such person's execution, delivery, furnishing or filing of the applicable document. This power of attorney shall be valid from the date hereof and shall remain in full force and effect until either revoked in writing by the Company, or, in respect of any attorney-in-fact named herein, until such person ceases to be an employee of the Company or one of its affiliates. IN WITNESS WHEREOF, the undersigned has caused this power of attorney to be executed as of this 9th day of December, 2022. Janus Henderson Group plc By: /s/ Michelle Rosenberg Name: Michelle Rosenberg Title: General Counsel and Company Secretary

FAQ

How many Mirum Pharmaceuticals (MIRM) shares does Janus Henderson report owning?

The filing reports an aggregate of 5,236,277 shares, representing about 10.6% of the class; a named subsidiary (JHIUS) is reported with 5,140,740 shares (~10.4%).

Does Janus Henderson have voting control over the MIRM shares?

No; the filing states 0 shares with sole voting power and reports the position under shared voting and shared dispositive power.

Is Janus Henderson holding the shares to influence control of Mirum?

The filing includes a certification that the securities are held in the ordinary course of business and were not acquired to change or influence control.

Which Janus Henderson entities are involved in these holdings?

The filing identifies indirect subsidiaries including JHIUS, JHIUKL and JHIAIFML as registered investment advisers involved with managed portfolios.

Does the filing indicate any planned corporate actions or group dissociation?

No; Items regarding group dissolution and related disclosures are marked N/A in the filing.