Perceptive reports 5.1% stake in Rhythm Pharmaceuticals

Rhythm Pharmaceuticals amended a Schedule 13G to report beneficial ownership stakes held by Perceptive-affiliated entities and Joseph Edelman.

Rhea-AI Filing Summary

Rhythm Pharmaceuticals amended a Schedule 13G to report beneficial ownership stakes held by Perceptive-affiliated entities and Joseph Edelman. The filing lists a combined 3,519,626 shares reported for Perceptive Advisors and shows the ownership percentages based on 68,532,607 shares outstanding as of May 1, 2026. The filing states the Master Fund directly holds 2,373,795 shares plus 416,666 shares issuable on conversion of Series A Convertible Preferred Stock, and Capital Solutions Holdings holds 729,165 shares issuable on conversion. The reported percentages are 5.1% for Perceptive Advisors and Mr. Edelman, 4.1% for the Master Fund, and 1.1% for Capital Solutions Holdings.

Insights

Institutional Ownership Analyst

Perceptive-affiliated entities report modest, disclosed stakes in Rhythm based on conversion treatment.

The filing specifies 3,519,626 shared voting and dispositive shares attributable to Perceptive Advisors and 68,532,607 shares outstanding as of May 1, 2026, with conversion of Series A Preferred applied at the stated rate. The numbers are explicit and tied to the issuer's Form 10-Q reference.

Cash‑flow treatment is not addressed; the filing documents beneficial ownership structure and voting/dispositive power. Subsequent filings would show any change in position; timing and transaction intent are not disclosed here.

Corporate Governance Specialist

Ownership is reported as shared power across related entities and a managing member.

The report attributes shared voting and dispositive power to Perceptive Advisors, Perceptive Life Sciences Master Fund, Ltd., Perceptive Capital Solutions Holdings, and Joseph Edelman as managing member. It describes managerial and advisory relationships that explain the shared attribution.

This filing is a disclosure of beneficial ownership and governance linkage; it does not report transactions or changes in control mechanics.

Key Figures

Shares outstanding: 68,532,607 shares Perceptive Advisors reported shares: 3,519,626 shares Perceptive Advisors ownership %: 5.1% +3 more

6 metrics

Shares outstanding 68,532,607 shares as of May 1, 2026

Perceptive Advisors reported shares 3,519,626 shares shared voting and dispositive power

Perceptive Advisors ownership % 5.1% percent of class reported

Master Fund direct holdings 2,373,795 shares directly held common stock

Master Fund convertible shares 416,666 shares issuable upon conversion of Series A Preferred

Capital Solutions convertible shares 729,165 shares issuable upon conversion of Series A Preferred

Key Terms

Series A Convertible Preferred Stock, Beneficial ownership, Shared dispositive power

3 terms

Series A Convertible Preferred Stock financial

"Series A Convertible Preferred Stock convertible into 416,666 shares"

Series A convertible preferred stock is a class of shares sold in an early funding round that gives investors a mix of protection and upside: it pays a priority claim over common shares if the company is sold or closes, but can be converted into ordinary shares to share in future growth. Think of it like a hybrid between a safer stake and a ticket to ownership; it matters to investors because it affects who controls the company, how future gains are split, and how much their investment is protected from downside.

Beneficial ownership regulatory

"Amount beneficially owned: The information required by this item"

Beneficial ownership means the person or entity that actually enjoys the benefits of owning shares or other assets — such as receiving dividends, voting rights, or price gains — even if the legal title is held in another name. For investors it matters because knowing who truly controls and profits from a company reveals who can influence decisions, exposes potential conflicts of interest or hidden concentration of power, and affects transparency and risk in the stock.

Shared dispositive power corporate

"Shared Dispositive Power 3,519,626.00"

FAQ

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

What stake does Perceptive Advisors report in RHYTM?

Perceptive Advisors reports beneficial ownership of 3,519,626 shares, representing 5.1% of the class based on 68,532,607 shares outstanding as of May 1, 2026. The amount reflects shares held directly and convertible preferred treated at the stated conversion rate.

How many shares does Perceptive Life Sciences Master Fund hold in RHYTM?

The Master Fund directly holds 2,373,795 shares and holds Series A Convertible Preferred Stock convertible into 416,666 shares, totaling the figures used to calculate a 4.1% ownership stake as reported.

What ownership percentage is Joseph Edelman reported to have in RHYTM?

Joseph Edelman is reported with a beneficial ownership percentage of 5.1%, reflecting his role as managing member of Perceptive Advisors and the combined shared holdings attributed to related entities in the filing.

What outstanding share count does the filing use to calculate percentages?

The filing uses 68,532,607 shares outstanding as of May 1, 2026, citing the issuer's Form 10-Q, and applies the conversion rate for Series A Convertible Preferred Stock to compute the reported percentages.

Does this Schedule 13G/A disclose recent purchases or sales?

No; this amendment discloses beneficial ownership levels and voting/dispositive power across related entities. It does not report transaction activity or timing of trades in the provided excerpt.

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

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Accepted by SEC EDGAR 05/15/2026 - 04:00 PM Learn about SEC filing dates

SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Amendment No. 2)

RHYTHM PHARMACEUTICALS, INC.

(Name of Issuer)

Common Stock, $0.001 par value per share

(Title of Class of Securities)

76243J105

(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): 76243J105

1

Names of Reporting Persons

Perceptive Advisors LLC

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 3,519,626.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,519,626.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,519,626.00

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)

5.1 %

12

Type of Reporting Person (See Instructions)

IA

SCHEDULE 13G

CUSIP Number(s): 76243J105

1

Names of Reporting Persons

Joseph Edelman

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 0.00
6	Shared Voting Power 3,519,626.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 3,519,626.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

3,519,626.00

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)

5.1 %

12

Type of Reporting Person (See Instructions)

IN

SCHEDULE 13G

CUSIP Number(s): 76243J105

1

Names of Reporting Persons

Perceptive Life Sciences Master Fund, Ltd.

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

CAYMAN ISLANDS

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 2,790,461.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 2,790,461.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

2,790,461.00

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)

4.1 %

12

Type of Reporting Person (See Instructions)

CO

SCHEDULE 13G

CUSIP Number(s): 76243J105

1

Names of Reporting Persons

Perceptive Capital Solutions Holdings LP

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

DELAWARE

Number of Shares Beneficially Owned by Each Reporting Person With:

5	Sole Voting Power 0.00
6	Shared Voting Power 729,165.00
7	Sole Dispositive Power 0.00
8	Shared Dispositive Power 729,165.00

9

Aggregate Amount Beneficially Owned by Each Reporting Person

729,165.00

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)

1.1 %

12

Type of Reporting Person (See Instructions)

PN

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, MA 02116
Item 2.
(a)	Name of person filing: The names of the persons filing this report (collectively, the "Reporting Persons") with respect to shares of Common Stock, $0.001 par value per share (the "Common Stock") of RHYTHM PHARMACEUTICALS, INC. (the "Issuer") are: (i) Perceptive Advisors LLC ("Perceptive Advisors") (ii) Joseph Edelman ("Mr. Edelman") (iii) Perceptive Life Sciences Master Fund, Ltd. (the "Master Fund") (iv) Perceptive Capital Solutions Holdings LP ("Capital Solutions Holdings")
(b)	Address or principal business office or, if none, residence: The address of the principal business office of each of the Reporting Persons is: 51 Astor Place, 10th Floor, New York, NY 10003
(c)	Citizenship: Perceptive Advisors is a Delaware limited liability company. Mr. Edelman is a United States citizen. The Master Fund is a Cayman Islands corporation. Capital Solutions Holdings is a Delaware Limited Liability Company.
(d)	Title of class of securities: Common Stock, $0.001 par value per share
(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: The information required by this item with respect to each Reporting Person is set forth in Rows 5 through 9 of the cover pages to this Schedule 13G. The ownership percentages reported are based on 68,532,607 shares of Common Stock outstanding as of May 1, 2026, as reported by the Issuer in its Quarterly Report on Form 10-Q filed with the Securities and Exchange Commission on May 5, 2026, and give effect to the conversion of shares of the Issuer's Series A Convertible Preferred Stock, par value $0.001 per share (the "Series A Convertible Preferred Stock"), held by the Reporting Persons at the current conversion rate of 20.8333 shares of Common Stock issuable upon the conversion of each $1,000 of liquidation preference. The Master Fund directly holds 2,373,795 shares of Common Stock. The Master Fund holds Series A Convertible Preferred Stock convertible into 416,666 shares of Common Stock. Capital Solutions Holdings holds Series A Convertible Preferred Stock convertible into 729,165 shares of Common Stock. Perceptive Advisors serves as the investment manager to the Master Fund and may be deemed to beneficially own the shares held by the Master Fund. Perceptive Capital Solutions Advisors LP serves as the investment manager to Capital Solutions Holdings and may be deemed to beneficially own the shares held by Capital Solutions Holdings. Perceptive Capital Solutions GP LLC is the general partner of Capital Solutions Holdings and is managed by Perceptive Capital Solutions Advisors LP, a relying adviser of Perceptive Advisors. Mr. Edelman is the managing member of Perceptive Advisors and may be deemed to beneficially own the shares held by the Master Fund and Capital Solutions Holdings.
(b)	Percent of class: Perceptive Advisors: 5.1% Mr. Edelman: 5.1% Master Fund: 4.1% Capital Solutions Holdings: 1.1%
(c)	Number of shares as to which the person has:
	(i) Sole power to vote or to direct the vote: Perceptive Advisors: 0 Mr. Edelman: 0 Master Fund: 0 Capital Solutions Holdings: 0
	(ii) Shared power to vote or to direct the vote: Perceptive Advisors: 3,519,626 Mr. Edelman: 3,519,626 Master Fund: 2,790,461 Capital Solutions Holdings: 729,165
	(iii) Sole power to dispose or to direct the disposition of: Perceptive Advisors: 0 Mr. Edelman: 0 Master Fund: 0 Capital Solutions Holdings: 0
	(iv) Shared power to dispose or to direct the disposition of: Perceptive Advisors: 3,519,626 Mr. Edelman: 3,519,626 Master Fund: 2,790,461 Capital Solutions Holdings: 729,165
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.
	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 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.

Perceptive Advisors LLC

Signature:	/s/ Joseph Edelman
Name/Title:	Joseph Edelman, Managing Member
Date:	05/15/2026

Joseph Edelman

Signature:	/s/ Joseph Edelman
Name/Title:	Joseph Edelman
Date:	05/15/2026

Perceptive Life Sciences Master Fund, Ltd.

Signature:	/s/ Joseph Edelman
Name/Title:	Joseph Edelman, Managing Member
Date:	05/15/2026

Perceptive Capital Solutions Holdings LP

Signature:	/s/ Joseph Edelman
Name/Title:	Joseph Edelman, Managing Member
Date:	05/15/2026