Insmed (INSM) CEO Lewis exercises stock options and sells shares under 10b5-1 plan

Rhea-AI Filing Summary

INSMED Inc.’s Chair and CEO William Lewis reported option exercises and share sales on common stock. On February 9, 2026, he exercised stock options for 4,440 shares at $17.16 and 6,259 shares at $30.46 per share, converting them into common stock. The same day, he sold 4,888 shares at a weighted average price of $147.17, 7,221 shares at $148.02, and 1,287 shares at $148.83, under a Rule 10b5-1 trading plan adopted on September 4, 2025. After these transactions, he directly owned 301,185 common shares and had 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)
02/09/2026

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	02/09/2026		M(1)		4,440	A	$17.16	308,322	D
Common Stock	02/09/2026		M(1)		6,259	A	$30.46	314,581	D
Common Stock	02/09/2026		S(1)		4,888	D	$147.17(2)	309,693	D
Common Stock	02/09/2026		S(1)		7,221	D	$148.02(3)	302,472	D
Common Stock	02/09/2026		S(1)		1,287	D	$148.83(4)	301,185	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)	$17.16	02/09/2026		M(1)			4,440	(5)	05/17/2027	Common Stock	4,440	$0	48,840	D
Stock Option (right to buy)	$30.46	02/09/2026		M(1)			6,259	(5)	01/04/2028	Common Stock	6,259	$0	68,850	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 4,888 shares sold at prices ranging from $146.61 to $147.60 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 7,221 shares sold at prices ranging from $147.61 to $148.60 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 1,287 shares sold at prices ranging from $148.62 to $149.35 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. 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	02/11/2026
	** 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.
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 did INSM (Insmed) CEO William Lewis report in this Form 4?

William Lewis reported exercising stock options into common shares and then selling portions of that stock. All sales occurred on February 9, 2026 and were executed under a pre-arranged Rule 10b5-1 trading plan adopted on September 4, 2025.

How many INSM stock options did William Lewis exercise on February 9, 2026?

On February 9, 2026, William Lewis exercised options for 4,440 shares at $17.16 and 6,259 shares at $30.46. These option exercises converted derivative securities into INSMED Inc. common stock according to the vesting terms described in the filing’s footnotes.

At what prices did William Lewis sell INSM common shares on February 9, 2026?

He sold 4,888 shares at a weighted average price of $147.17, 7,221 shares at $148.02, and 1,287 shares at $148.83. Each weighted average reflects multiple trades within narrow price ranges detailed in the explanatory footnotes.

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

After the reported transactions, William Lewis directly owned 301,185 INSM common shares. He also had indirect ownership of 233,924 shares through the Katie Procter Dynasty Trust and 50,500 shares through the William Lewis Family Legacy Trust, as disclosed in the filing tables.

Was the INSM CEO’s stock sale part of a 10b5-1 trading plan?

Yes. The filing states the transactions were executed under a Rule 10b5-1 trading plan adopted on September 4, 2025. Such plans allow insiders to pre-schedule trades, helping separate personal trading decisions from later material nonpublic information.

What vesting terms applied to William Lewis’s exercised INSM stock options?

The options vested 25% on the first anniversary of the grant date, then an additional 12.5% on each six-month anniversary through the fourth anniversary. This schedule created multiple exercisable tranches, two of which Lewis exercised on February 9, 2026, as described in the filing.