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

Rhea-AI Filing Summary

Primecap Management Co./CA reports beneficial ownership of 4,878,037 shares of Rhythm Pharmaceuticals, representing 7.67% of the common stock. The filing is an Amendment No. 10 to a Schedule 13G and lists an event date of 06/30/2025. Primecap reports sole voting and sole dispositive power over these shares, and certifies the shares were acquired and are held in the ordinary course of business and not to change or influence control of the issuer. The filing names Rhythm Pharmaceuticals' principal executive offices at the address provided and shows Primecap's business address in Pasadena, California. The form is signed by Jorge A. Rodriguez, Deputy Chief Compliance Officer, dated 08/13/2025.

Insights

Securities Analyst

TL;DR: Primecap holds a material 7.67% passive stake in RYTM with sole voting/dispositive power disclosed on Schedule 13G/A.

Primecap Management reports beneficial ownership of 4,878,037 shares, equal to 7.67% of Rhythm Pharmaceuticals' common stock. The filing identifies Primecap as an IA (investment adviser) and states the position is held in the ordinary course of business and not for the purpose of changing control. For investors, the key facts are the size of the stake and that Primecap asserts a passive intent, which keeps this disclosure in the realm of institutional interest rather than activist intent.

Corporate Governance Expert

TL;DR: A >5% holding with sole voting power is material to disclosure but the filer certifies no intent to influence control.

The Schedule 13G/A shows sole voting and dispositive power for 4,878,037 shares (7.67%), which triggers reporting obligations. The certification in Item 10 explicitly states the position is not held to change or influence control. From a governance perspective, the form documents a significant passive ownership stake and provides the issuer and market with necessary transparency about an institutional holder.

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 10)

Rhythm Pharmaceuticals, Inc.

(Name of Issuer)

COM

(Title of Class of Securities)

76243J105

(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. 76243J105

1

Names of Reporting Persons

PRIMECAP MANAGEMENT CO/CA/

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

UNITED STATES

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 4,878,037.00
6	Shared Voting Power 0.00
7	Sole Dispositive Power 4,878,037.00
8	Shared Dispositive Power 0.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

4,878,037.00

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)

7.67 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

Item 1.
(a)	Name of issuer: Rhythm Pharmaceuticals, Inc.
(b)	Address of issuer's principal executive offices: 222 Berkeley Street, 12th Floor, Boston, CALIFORNIA 02116
Item 2.
(a)	Name of person filing: PRIMECAP MANAGEMENT CO/CA/
(b)	Address or principal business office or, if none, residence: 177 EAST COLORADO BLVD. 11TH FLOOR PASADENA, California 91105
(c)	Citizenship: PRIMECAP MANAGEMENT CO/CA/ - UNITED STATES
(d)	Title of class of securities: COM
(e)	CUSIP No.: 76243J105
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: 4,878,037
(b)	Percent of class: 7.67 %
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: PRIMECAP MANAGEMENT CO/CA/ - 4,878,037
	(ii) Shared power to vote or to direct the vote: PRIMECAP MANAGEMENT CO/CA/ - 0
	(iii) Sole power to dispose or to direct the disposition of: PRIMECAP MANAGEMENT CO/CA/ - 4,878,037
	(iv) Shared power to dispose or to direct the disposition of: PRIMECAP MANAGEMENT CO/CA/ - 0
Item 5.	Ownership of 5 Percent or Less of a Class.
Item 6.	Ownership of more than 5 Percent on Behalf of Another Person.
	Not Applicable
Item 7.	Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on by the Parent Holding Company or Control Person.
	Not Applicable
Item 8.	Identification and Classification of Members of the Group.
	Not Applicable
Item 9.	Notice of Dissolution of Group.
	Not Applicable

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.

PRIMECAP MANAGEMENT CO/CA/

Signature:	Jorge A. Rodriguez
Name/Title:	Deputy Chief Compliance Officer
Date:	08/13/2025

FAQ

How many Rhythm Pharmaceuticals (RYTM) shares does Primecap Management report owning?

Primecap reports owning 4,878,037 shares of Rhythm Pharmaceuticals common stock.

What percentage of RYTM does Primecap's holding represent?

The filing states the holdings represent 7.67% of the class.

Does Primecap have voting power over these shares?

Yes. The filer reports sole voting power and sole dispositive power for the 4,878,037 shares.

When is the event date and when was the form signed?

The event date shown is 06/30/2025 and the signature date on the filing is 08/13/2025.

Does the filing state Primecap intends to influence control of Rhythm Pharmaceuticals?

No. Item 10 certifies the securities were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing control.