[Form 4] Rhythm Pharmaceuticals, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Hunter C. Smith, Chief Financial Officer of Rhythm Pharmaceuticals, Inc. (RYTM), reported option exercises and share sales on August 12-13, 2025. The filing shows Mr. Smith exercised 24,611 stock options at an exercise price of $6.88 on August 12, 2025, and 3,477 options at the same exercise price on August 13, 2025, resulting in 28,088 shares underlying those exercises.

Concurrent with the August 12 exercise, 24,611 shares were sold under a Rule 10b5-1 plan at a weighted-average price of $96.3322 per share (individual sale prices ranged $96.00–$96.63). On August 13, 3,477 shares were sold at $96.00 per share. After these transactions the reporting person owned 116,915 shares beneficially. The Form 4 notes the 10b5-1 plan was adopted February 28, 2025, and the stock options were fully vested.

Positive

• Options exercised at a low strike: Exercised stock options at a $6.88 exercise price, converting in-the-money options into common shares.
• Use of Rule 10b5-1 plan: Sales effected pursuant to a 10b5-1 plan adopted February 28, 2025, which documents prearranged trading and supports compliance.

Negative

• Substantial insider sales: Sale of 28,088 shares at prices ~ $96 reduces insider shareholding and may be viewed by some investors as insider liquidity.
• Large weighted-average sale price range: Sales occurred across a range ($96.00–$96.63) with only weighted-average disclosed, requiring requests for per-trade detail if more granularity is needed.

Insights

Securities Analyst

TL;DR: Insider exercised vested options and sold most of the resulting shares under a 10b5-1 plan at ~ $96 per share.

The transactions are routine for option exercise monetization: Mr. Smith exercised in-the-money options ($6.88 strike) and sold the majority of resulting shares under a pre-established Rule 10b5-1 plan adopted February 28, 2025. The weighted-average sale price of $96.3322 implies substantial realized proceeds relative to the exercise cost, and the filing confirms continued beneficial ownership of 116,915 shares after the sales. This is informational for shareholders tracking insider liquidity but does not, by itself, indicate a change in company fundamentals.

Corporate Governance Expert

TL;DR: Transactions were executed under a documented 10b5-1 plan and the options were fully vested, which supports procedural compliance.

The Form 4 discloses a properly documented sequence: adoption date of the trading plan is provided and the sale footnote transparently lists the sale price range and weighted-average price. The signature by an attorney-in-fact is included. These elements align with good governance practices for insider trading disclosure and reduce regulatory ambiguity about timing or intent.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

X

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Smith Hunter C

(Last) (First) (Middle)

C/O RHYTHM PHARMACEUTICALS, INC.

222 BERKELEY STREET, 12TH FLOOR

(Street)

BOSTON MA 02116

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
RHYTHM PHARMACEUTICALS, INC. [ RYTM ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Financial Officer

3. Date of Earliest Transaction (Month/Day/Year)
08/12/2025

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	08/12/2025		M		24,611	A	$6.88	141,526	D
Common Stock	08/12/2025		S(1)		24,611	D	$96.3322(2)	116,915	D
Common Stock	08/13/2025		M		3,477	A	$6.88	120,392	D
Common Stock	08/13/2025		S(1)		3,477	D	$96	116,915	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Stock Options (Right to Buy)	$6.88	08/12/2025		M			24,611	(3)	08/08/2027	Common Stock	24,611	$0	3,477	D
Stock Options (Right to Buy)	$6.88	08/13/2025		M			3,477	(3)	08/08/2027	Common Stock	3,477	$0	0	D

Explanation of Responses:

1. The sale reported in the Form 4 was effected pursuant to a Rule 10b5-1 plan adopted by the Reporting Person on February 28, 2025.

2. The price reported in Column 4 is a weighted average price. The securities were sold in multiple transactions at prices ranging from $96.00 to $96.63 per common stock. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the range set forth in this footnote.

3. The stock option is fully vested.

	/s/ Stephen Vander Stoep, attorney-in-fact for Hunter C. Smith	08/14/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What transactions did RYTM CFO Hunter C. Smith report on Form 4?

He exercised 24,611 options on 08/12/2025 and 3,477 options on 08/13/2025 and sold those shares under a 10b5-1 plan.

At what prices were the RYTM shares sold by Hunter C. Smith?

Shares sold on 08/12/2025 had a weighted-average price of $96.3322 (individual prices ranged $96.00–$96.63); shares sold on 08/13/2025 were sold at $96.00.

How many RYTM shares does Hunter C. Smith beneficially own after these transactions?

He beneficially owned 116,915 shares following the reported transactions.

Were the stock options exercised by the reporting person vested?

Yes, the filing states the stock options exercised are fully vested.

When was the 10b5-1 plan that governed the sales adopted?

The Form 4 notes the 10b5-1 plan was adopted on February 28, 2025.