INSMED CEO exercises options, sells 10,699 shares

INSMED Inc Chair and CEO William Lewis exercised stock options and sold shares in INSMED Inc. On April 16, 2026, he exercised options for 10,699 shares of Common Stock at exercise prices of $30.46 and $17.16 per share.

Rhea-AI Filing Summary

INSMED Inc Chair and CEO William Lewis exercised stock options and sold shares in INSMED Inc. On April 16, 2026, he exercised options for 10,699 shares of Common Stock at exercise prices of $30.46 and $17.16 per share.

That same day he sold a total of 10,699 shares of Common Stock in open-market transactions at weighted average prices between $142.39 and $146.02 per share under a pre-arranged Rule 10b5-1 trading plan. After these transactions he directly held 301,185 shares, with an additional 233,924 shares held indirectly by a trust.

Insider Trade Summary 10b5-1

Exercise and Sale: 10,699 shares ($1.27M approx. pre-tax spread)

Exercise and Sale 9 txns

Insider Lewis William

Role Chair and CEO

Sold 10,699 shs ($1.54M)

Approx. gross sale proceeds $1.54M

Approx. exercise cost $267K

Approx. pre-tax spread $1.27M

Type	Security	Shares	Price	Value
Exercise	Stock Option (right to buy)	6,259	$0.00	$0.00
Exercise	Stock Option (right to buy)	4,440	$0.00	$0.00
Exercise	Common Stock	6,259	$30.46	$191K
Exercise	Common Stock	4,440	$17.16	$76K
Sale	Common Stock	2,246	$142.99	$321K
Sale	Common Stock	5,373	$143.81	$773K
Sale	Common Stock	2,255	$144.66	$326K
Sale	Common Stock	825	$145.79	$120K
holding	Common Stock	--	--	--

Holdings After Transaction: Stock Option (right to buy) — 64,195 contracts (Direct); Common Stock — 301,185 shares (Direct); Common Stock — 233,924 shares (Indirect, By trust)

Footnotes (6)

1. F1. 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. F2. This is the weighted average sales price representing 2,246 shares sold at prices ranging from $142.39 to $143.38 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. F3. This is the weighted average sales price representing 5,373 shares sold at prices ranging from $143.39 to $144.32 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.
4. F4. This is the weighted average sales price representing 2,255 shares sold at prices ranging from $144.40 to $145.20 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. F5. This is the weighted average sales price representing 825 shares sold at prices ranging from $145.53 to $146.02 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. F6. 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.

Key Figures

Options exercised: 10,699 shares Exercise prices: $30.46 and $17.16 per share Shares sold: 10,699 shares +5 more

8 metrics

Options exercised 10,699 shares Stock option exercises on April 16, 2026

Exercise prices $30.46 and $17.16 per share Strike prices of exercised stock options

Shares sold 10,699 shares Open-market sales on April 16, 2026

Sale prices $142.39–$146.02 per share Weighted average sales price ranges from footnotes

Direct holdings after 301,185 shares Common stock directly owned after transactions

Indirect holdings after 233,924 shares Common stock held indirectly by trust

Net buy/sell direction Net sell of 10,699 shares Form 4 transaction summary

10b5-1 plan adoption date September 4, 2025 Footnote describing pre-arranged trading plan

Key Terms

Rule 10b5-1 trading plan, Stock Option (right to buy), weighted average sales price, open-market sale, +1 more

5 terms

Rule 10b5-1 trading plan regulatory

"This transaction was effected pursuant to a 10b5-1 trading plan adopted by the Reporting Person"

A Rule 10b5-1 trading plan is a pre-arranged schedule that allows company insiders to buy or sell stock at specific times, even if they have inside information. It helps prevent accusations of unfair trading by making these transactions look planned and transparent, rather than sneaky or illegal.

Stock Option (right to buy) financial

"security_title: Stock Option (right to buy)"

weighted average sales price financial

"This is the weighted average sales price representing 2,246 shares sold at prices ranging"

open-market sale financial

"transaction_action: open-market sale"

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

vesting schedule financial

"The options became exercisable based on the following vesting schedule: 25% vested"

A vesting schedule is a timeline that determines when someone gains full ownership of certain benefits, such as company stock or retirement contributions. Think of it like earning the right to own a gift gradually over time, rather than receiving it all at once. It matters to investors because it affects when they can fully access or sell these benefits, influencing their financial planning and decision-making.

FAQ

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

What did INSMED (INSM) CEO William Lewis do in this Form 4 filing?

William Lewis exercised stock options and sold shares of INSMED common stock. He exercised options for 10,699 shares, then sold 10,699 shares in open-market transactions while remaining a significant shareholder after the trades.

How many INSMED (INSM) shares did the CEO sell and at what prices?

He sold 10,699 shares of INSMED common stock. The weighted average sales prices ranged from about $142.39 to $146.02 per share across several trades, as detailed in the filing’s transaction and footnote disclosures.

What stock options did the INSMED (INSM) CEO exercise in this filing?

He exercised stock options covering 10,699 shares of INSMED common stock. The exercise prices were $30.46 and $17.16 per share, converting previously granted options into common shares before the reported open-market sales.

How many INSMED (INSM) shares does the CEO own after these transactions?

Following the reported trades, William Lewis directly held 301,185 INSMED common shares. The filing also shows an additional 233,924 shares held indirectly by a trust, reflecting both his direct and indirect ownership positions after the activity.

Were the INSMED (INSM) CEO’s stock sales made under a Rule 10b5-1 plan?

Yes. A footnote states the transactions were effected pursuant to a Rule 10b5-1 trading plan adopted on September 4, 2025. Such plans are pre-arranged programs that schedule trades in advance under SEC rules.

What is the net effect of this Form 4 on the CEO’s INSMED (INSM) share count?

The CEO exercised and sold 10,699 shares, resulting in net reported selling of 10,699 shares. Despite this, he still holds 301,185 shares directly plus 233,924 shares indirectly through a trust, according to the filing summary.

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

Form 4 Insider Transactions: What Each Field Means →

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Accepted by SEC EDGAR 04/17/2026 - 04:43 PM Learn about SEC filing dates

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).

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 NEW JERSEY 08807

(City) (State) (Zip)

UNITED STATES

(Country)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/16/2026

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

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

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

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	04/16/2026		M(1)		6,259	A	$30.46	307,444	D
Common Stock	04/16/2026		M(1)		4,440	A	$17.16	311,884	D
Common Stock	04/16/2026		S(1)		2,246	D	$142.99(2)	309,638	D
Common Stock	04/16/2026		S(1)		5,373	D	$143.81(3)	304,265	D
Common Stock	04/16/2026		S(1)		2,255	D	$144.66(4)	302,010	D
Common Stock	04/16/2026		S(1)		825	D	$145.79(5)	301,185	D
Common Stock								233,924	I	By 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	04/16/2026		M(1)			6,259	(6)	01/04/2028	Common Stock	6,259	$0	37,555	D
Stock Option (right to buy)	$17.16	04/16/2026		M(1)			4,440	(6)	05/17/2027	Common Stock	4,440	$0	26,640	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 2,246 shares sold at prices ranging from $142.39 to $143.38 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 5,373 shares sold at prices ranging from $143.39 to $144.32 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.

4. This is the weighted average sales price representing 2,255 shares sold at prices ranging from $144.40 to $145.20 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 825 shares sold at prices ranging from $145.53 to $146.02 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. 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	04/17/2026
	** 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.
* Form 4: SEC 1474 (03-26)