Insmed (INSM) CEO William Lewis exercises options and sells shares

Rhea-AI Filing Summary

Insmed Inc. Chair and CEO William Lewis reported a series of option exercises and related stock sales on January 20, 2026 under a pre-arranged Rule 10b5-1 trading plan adopted on September 4, 2025. He exercised stock options to acquire 6,259 shares at an exercise price of $30.46 per share and 4,440 shares at $17.16 per share, both at a cost of $0 per derivative security.

On the same date, Lewis reported open-market sales of Insmed common stock in several tranches, including 1,006 shares at a weighted average price of $156.80, 1,243 shares at $158.37, 5,967 shares at $158.99, 2,229 shares at $159.85, and 254 shares at $160.70, with each weighted average representing sales within stated price ranges. Following these transactions, Lewis directly owned 306,891 shares of common stock and held options covering 75,109 and 53,280 shares in two grants. The filing also reports indirect ownership of 233,924 shares through the Katie Procter Dynasty Trust and 50,500 shares through the William Lewis Family Legacy Trust.

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

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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^*

Lewis William

(Last) (First) (Middle)

700 US HIGHWAY 202/206

(Street)

BRIDGEWATER NJ 08807

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
INSMED Inc [ INSM ]

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

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chair and CEO

3. Date of Earliest Transaction (Month/Day/Year)
01/20/2026

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	01/20/2026		M(1)		6,259	A	$30.46	313,150	D
Common Stock	01/20/2026		M(1)		4,440	A	$17.16	317,590	D
Common Stock	01/20/2026		S(1)		1,006	D	$156.8(2)	316,584	D
Common Stock	01/20/2026		S(1)		1,243	D	$158.37(3)	315,341	D
Common Stock	01/20/2026		S(1)		5,967	D	$158.99(4)	309,374	D
Common Stock	01/20/2026		S(1)		2,229	D	$159.85(5)	307,145	D
Common Stock	01/20/2026		S(1)		254	D	$160.7(6)	306,891	D
Common Stock								233,924	I	By the Katie Procter Dynasty Trust
Common Stock								50,500	I	By the William Lewis Family Legacy Trust

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 Option (right to buy)	$30.46	01/20/2026		M(1)			6,259	(7)	01/04/2028	Common Stock	6,259	$0	75,109	D
Stock Option (right to buy)	$17.16	01/20/2026		M(1)			4,440	(7)	05/17/2027	Common Stock	4,440	$0	53,280	D

Explanation of Responses:

1. This transaction was effected pursuant to a 10b5-1 trading plan adopted by the Reporting Person on September 4, 2025 in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended.

2. This is the weighted average sales price representing 1,006 shares sold at prices ranging from $156.53 to $157.50 per share. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer the number of shares sold at each price within the price range upon request.

3. This is the weighted average sales price representing 1,243 shares sold at prices ranging from $157.54 to $158.53 per share. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer the number of shares sold at each price within the price range upon request.

4. This is the weighted average sales price representing 5,967 shares sold at prices ranging from $158.55 to $159.52 per share. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer the number of shares sold at each price within the price range upon request.

5. This is the weighted average sales price representing 2,229 shares sold at prices ranging from $159.55 to $160.32 per share. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer the number of shares sold at each price within the price range upon request.

6. This is the weighted average sales price representing 254 shares sold at prices ranging from $160.58 to $160.76 per share. The Reporting Person undertakes to provide to the SEC staff, the issuer, or a security holder of the issuer the number of shares sold at each price within the price range upon request.

7. The options became exercisable based on the following vesting schedule: 25% vested on the first anniversary of the grant date and an additional 12.5% vested on each sixth month anniversary date thereafter through the fourth anniversary of the date of grant.

Remarks:

	/s/ William Lewis, by Michael A. Smith as Attorney-in-fact	01/22/2026
	** 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.
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FAQ

What insider transactions did INSM Chair and CEO William Lewis report on January 20, 2026?

On January 20, 2026, William Lewis reported exercising stock options to acquire 6,259 Insmed common shares at $30.46 and 4,440 shares at $17.16 per share, and selling multiple blocks of common stock at weighted average prices between $156.80 and $160.70 per share.

Were the INSM insider trades by William Lewis made under a 10b5-1 plan?

Yes. The filing states that the transactions were effected pursuant to a Rule 10b5-1 trading plan adopted by William Lewis on September 4, 2025 in accordance with the Securities Exchange Act of 1934.

How many INSM shares does William Lewis own after these transactions?

After the reported transactions, William Lewis directly owned 306,891 shares of Insmed common stock. He is also reported as indirectly owning 233,924 shares through the Katie Procter Dynasty Trust and 50,500 shares through the William Lewis Family Legacy Trust.

What stock option positions in INSM does William Lewis hold following the Form 4 filing?

Following the transactions, William Lewis held stock options covering 75,109 shares with an exercise price of $30.46 per share, expiring on January 4, 2028, and options covering 53,280 shares with an exercise price of $17.16 per share, expiring on May 17, 2027.

What prices were the INSM shares sold for by William Lewis on January 20, 2026?

The Form 4 reports weighted average sale prices of $156.80 for 1,006 shares, $158.37 for 1,243 shares, $158.99 for 5,967 shares, $159.85 for 2,229 shares, and $160.70 for 254 shares, each representing shares sold within specified price ranges.

How do the INSM option grants reported by William Lewis vest?

The filing states that the options became exercisable under a schedule where 25% vested on the first anniversary of the grant date and an additional 12.5% vested on each six-month anniversary thereafter through the fourth anniversary of the grant date.

What indirect holdings in INSM stock are associated with William Lewis?

Indirect holdings reported include 233,924 shares of Insmed common stock held by the Katie Procter Dynasty Trust and 50,500 shares held by the William Lewis Family Legacy Trust, both shown as indirect ownership interests.