Janus Henderson reports 5.8% stake in Maze Therapeutics

Janus Henderson Group plc reports beneficial ownership of 2,858,876 shares of Maze Therapeutics, Inc. common stock, representing 5.8% of the class as of 03/31/2026.

Rhea-AI Filing Summary

Janus Henderson Group plc reports beneficial ownership of 2,858,876 shares of Maze Therapeutics, Inc. common stock, representing 5.8% of the class as of 03/31/2026. The filing states the holdings are held across Janus Henderson–managed portfolios, with shared voting and dispositive power of 2,858,876 shares and no sole voting or dispositive power. The filing notes the Asset Managers exercise voting discretion for client accounts and disclaim rights to dividends or sale proceeds tied to those accounts. The signature on the amendment is dated 5/15/2026.

Insights

Institutional Ownership Analyst

Large passive stake disclosed: 2,858,876 shares (5.8%).

Janus Henderson Group plc’s schedule shows an aggregated beneficial position of 2,858,876 shares held across multiple managed portfolios, equal to 5.8% of Maze Therapeutics common stock as of 03/31/2026. The position is reported with shared voting and dispositive power rather than sole control.

The filing describes that the Asset Managers exercise voting discretion for clients and disclaim dividend or sale proceeds rights tied to those accounts. Subsequent filings may clarify which specific advisory entities hold the positions.

Securities Compliance Specialist

Amendment clarifies group/parent reporting and disclosures.

The amendment identifies Janus Henderson Group plc as ultimate parent and lists multiple SEC-registered advisers that act as Asset Managers, consistent with aggregated Schedule 13G/A reporting practices. The filing attaches exhibits for subsidiary identification per Item 7.

Key qualifiers—shared voting/dispositive power and the Managed Portfolios’ dividend/proceeds rights—are preserved verbatim in the filing. Regulatory follow-up would rely on attached exhibits for precise entity-level classifications.

Key Figures

Beneficial ownership: 2,858,876 shares Percent of class: 5.8% Shared voting power: 2,858,876 shares +1 more

4 metrics

Beneficial ownership 2,858,876 shares as of <date>03/31/2026</date>

Percent of class 5.8% Maze Therapeutics common stock

Shared voting power 2,858,876 shares reported shared voting power

Sole voting/dispositive power 0 shares reported sole voting/dispositive power

Key Terms

beneficial owner, Managed Portfolios, Schedule 13G/A

3 terms

beneficial owner regulatory

"may be deemed to be the beneficial owner of 2,858,876 common stock"

A beneficial owner is the person who ultimately owns or controls a financial asset or property, even if their name isn't directly on official documents. Think of it like someone who secretly holds the keys to a safe deposit box—others may appear to have access, but the true owner is the one who benefits from what's inside. Identifying beneficial owners helps ensure transparency and prevent illegal activities like money laundering or fraud.

Managed Portfolios financial

"collectively referred to herein as Managed Portfolios"

Schedule 13G/A regulatory

"This amendment identifies reporting under Schedule 13G/A"

A Schedule 13G/A is an amended public filing with the U.S. securities regulator that updates a previous Schedule 13G, disclosing when an individual or group holds a substantial (typically over 5%) stake in a company and is claiming a passive, non‑controlling intent. Investors monitor these updates because rising or falling holdings can signal changing confidence, potential future moves, or shifts in voting power — like watching a public ledger where large shareholders quietly adjust their positions.

FAQ

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

What stake does Janus Henderson Group plc hold in MAZE?

Janus Henderson Group plc reports beneficial ownership of 2,858,876 shares, equal to 5.8% of Maze Therapeutics common stock as of 03/31/2026. The shares are held across multiple managed portfolios under Janus Henderson asset managers.

Does Janus Henderson have sole voting control over the MAZE shares?

No. The filing reports 0 shares with sole voting power and 2,858,876 shares with shared voting power. Voting and disposition are exercised by the Asset Managers on behalf of client accounts.

Are dividends or sale proceeds payable to Janus Henderson according to the filing?

The filing states the Asset Managers do not have the right to receive dividends or proceeds from sales of securities held in the managed portfolios and disclaim ownership tied to those rights.

What date does the reported ownership correspond to in this amendment?

The ownership amount is reported as of 03/31/2026 in the amendment. The signature date on the filing is 5/15/2026, which reflects when the amendment was executed.

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

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Accepted by SEC EDGAR 05/15/2026 - 12:37 PM EDT Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 3)

MAZE THERAPEUTICS, INC.

(Name of Issuer)

Common Stock

(Title of Class of Securities)

578784100

(CUSIP Number)

03/31/2026

(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)

schemaVersion:

SCHEDULE 13G

CUSIP Number(s): 578784100

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 2,858,876.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,858,876.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,858,876.00

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)

5.8 %

12

Type of Reporting Person (See Instructions)

HC

SCHEDULE 13G

Item 1.
(a)	Name of issuer: MAZE THERAPEUTICS, INC.
(b)	Address of issuer's principal executive offices: 171 OYSTER POINT BOULEVARD, SUITE 300 SOUTH SAN FRANCISCO, CA 94080
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.: 578784100
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: Janus Henderson Group plc (JHG) is the ultimate parent of a number of SEC-registered investment advisers and foreign equivalents thereof, including but not limited to Janus Henderson Investors US LLC, Janus Henderson Investors UK Limited, Janus Henderson Investors Australia Institutional Funds Management Limited, Janus Henderson Investors Middle East Limited, Janus Henderson Investors (Jersey) Limited, Janus Henderson Investors (Japan) Limited, Janus Henderson Investors (Singapore) Limited, Kapstream Capital Pty Limited, Privacore Capital Advisors LLC, Tabula Investment Management Limited, and Victory Park Capital Advisors LLC (each, an Asset Manager and together, the Asset Managers). The Asset Managers generally exercise investment and/or voting discretion on behalf of their clients which include investment companies, other investment advisers, institutional separate accounts and retail separate accounts (collectively referred to herein as Managed Portfolios). As a result of their exercise of investment and/or voting discretion on behalf of the Managed Portfolios, the Asset Managers may be deemed to be the beneficial owner of 2,858,876 common stock of Maze Therapeutics, Inc. However, the Asset Managers do not have the right to receive any dividends from, or the proceeds from the sale of, the securities held in the Managed Portfolios and disclaim any ownership associated with such rights.
(b)	Percent of class: 5.8 %
(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: 2858876
	(iii) Sole power to dispose or to direct the disposition of: 0
	(iv) Shared power to dispose or to direct the disposition of: 2858876
Item 5.	Ownership of 5 Percent or Less of a Class.
	Not Applicable
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. The Managed Portfolios have the right to receive all dividends from, and the proceeds from the sale of, the securities held in their respective accounts. Of the Managed Portfolios, none own more than five percent of the common stock of Maze Therapeutics, Inc.
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. Please refer to Exhibit 99.
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
Date:	5/15/2026

Exhibit Information

Exhibit 24: Power of Attorney Exhibit 99: Item 7