Were Insmed (INSM) CEO William Lewis’s share sales under a 10b5-1 plan?

Yes. The filing states the share sales were executed under a Rule 10b5-1 trading plan adopted on September 4, 2025. Such pre-arranged plans allow insiders to schedule trades in advance according to predetermined instructions.

What is William Lewis’s remaining direct Insmed (INSM) share ownership?

After the reported transactions, William Lewis directly owned 301,185 Insmed Common Stock shares. This figure reflects his holdings following both the stock option exercises that increased his shares and the open-market sales that reduced them.

Insmed (INSM) CEO Lewis exercises options and sells 10,699 shares

Filing Impact

(Very High)

Filing Sentiment

(Negative)

Form Type

Rhea-AI Filing Summary

Insmed Inc Chair and CEO William Lewis reported option exercises and share sales. On February 19, 2026, he exercised stock options for 6,259 and 4,440 shares, converting them into an equal number of Common Stock shares at grant prices of $30.46 and $17.16 per share.

On the same date, he sold a total of 10,699 Common Stock shares in open-market transactions at weighted average prices between $149.17 and $153.38, under a pre‑arranged Rule 10b5‑1 trading plan adopted on September 4, 2025. After these trades, he held 301,185 shares directly, plus indirect holdings of 233,924 shares through the Katie Procter Dynasty Trust and 50,500 shares through the William Lewis Family Legacy Trust.

Insider Trade Summary

Net Seller: 10,699 shares ($1,615,257)

Net Sell 11 txns

Insider Lewis William

Role Chair and CEO

Sold 10,699 shs ($1.62M)

Type	Security	Shares	Price	Value
Exercise	Stock Option (right to buy)	6,259	$0.00	--
Exercise	Stock Option (right to buy)	4,440	$0.00	--
Exercise	Common Stock	6,259	$30.46	$191K
Exercise	Common Stock	4,440	$17.16	$76K
Sale	Common Stock	1,988	$149.17	$297K
Sale	Common Stock	1,891	$150.10	$284K
Sale	Common Stock	3,413	$151.12	$516K
Sale	Common Stock	2,377	$151.92	$361K
Sale	Common Stock	1,030	$153.38	$158K
holding	Common Stock	--	--	--
holding	Common Stock	--	--	--

Holdings After Transaction: Stock Option (right to buy) — 62,591 shares (Direct); Common Stock — 307,444 shares (Direct); Common Stock — 233,924 shares (Indirect, By the Katie Procter Dynasty Trust)

Footnotes (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. This is the weighted average sales price representing 1,988 shares sold at prices ranging from $148.51 to $149.50 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. This is the weighted average sales price representing 1,891 shares sold at prices ranging from $149.53 to $150.50 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. This is the weighted average sales price representing 3,413 shares sold at prices ranging from $150.54 to $151.51 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. This is the weighted average sales price representing 2,377 shares sold at prices ranging from $151.56 to $152.43 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. This is the weighted average sales price representing 1,030 shares sold at prices ranging from $153.00 to $153.78 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. 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.

Form 4 Insider Transactions: What Each Field Means →

02/23/2026 - 04:34 PM

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
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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

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)
02/19/2026

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	02/19/2026		M⁽¹⁾		6,259	A	$30.46	307,444	D
Common Stock	02/19/2026		M⁽¹⁾		4,440	A	$17.16	311,884	D
Common Stock	02/19/2026		S⁽¹⁾		1,988	D	$149.17⁽²⁾	309,896	D
Common Stock	02/19/2026		S⁽¹⁾		1,891	D	$150.1⁽³⁾	308,005	D
Common Stock	02/19/2026		S⁽¹⁾		3,413	D	$151.12⁽⁴⁾	304,592	D
Common Stock	02/19/2026		S⁽¹⁾		2,377	D	$151.92⁽⁵⁾	302,215	D
Common Stock	02/19/2026		S⁽¹⁾		1,030	D	$153.38⁽⁶⁾	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option (right to buy)	$30.46	02/19/2026		M⁽¹⁾			6,259	⁽⁷⁾	01/04/2028	Common Stock	6,259	$0	62,591	D
Stock Option (right to buy)	$17.16	02/19/2026		M⁽¹⁾			4,440	⁽⁷⁾	05/17/2027	Common Stock	4,440	$0	44,400	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 1,988 shares sold at prices ranging from $148.51 to $149.50 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 1,891 shares sold at prices ranging from $149.53 to $150.50 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.

4. This is the weighted average sales price representing 3,413 shares sold at prices ranging from $150.54 to $151.51 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 2,377 shares sold at prices ranging from $151.56 to $152.43 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 1,030 shares sold at prices ranging from $153.00 to $153.78 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	02/23/2026
	** 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.

Source: View Original Filing on SEC EDGAR

FAQ

What insider transactions did Insmed (INSM) CEO William Lewis report?

William Lewis reported exercising stock options for 10,699 shares and selling 10,699 Common Stock shares. The sales occurred in multiple open-market trades at weighted average prices between $149.17 and $153.38 on February 19, 2026.

How many Insmed (INSM) shares did William Lewis sell and at what prices?

He sold 10,699 Common Stock shares in several open-market transactions. Weighted average sale prices ranged from $149.17 to $153.38 per share, with each transaction covering different blocks of shares within these price ranges.

What indirect Insmed (INSM) holdings are associated with William Lewis?

The filing lists 233,924 Common Stock shares held indirectly through the Katie Procter Dynasty Trust and 50,500 shares held indirectly through the William Lewis Family Legacy Trust. These positions are reported as indirect ownership interests associated with Lewis.

What stock options did Insmed (INSM) CEO William Lewis exercise?

He exercised stock options covering 6,259 and 4,440 shares of Common Stock. The options converted into shares at exercise prices of $30.46 and $17.16 per share, respectively, according to the reported transactions.