Insmed CEO reports option exercises and share sales

INSMED Inc Chair and CEO William Lewis reported a mix of stock sales and option exercises in company common stock.

Rhea-AI Filing Summary

INSMED Inc Chair and CEO William Lewis reported a mix of stock sales and option exercises in company common stock. On May 18, 2026, he sold a total of 25,564 shares in three open-market transactions at weighted average prices in the $105–$107 per share range, executed under a preset Rule 10b5-1 trading plan adopted on September 4, 2025.

On the same date, Lewis also exercised 10,699 stock options to acquire common shares, with exercise prices of $17.16 and $30.46 per share. The filing shows both direct holdings and additional shares held indirectly through a trust, indicating he retains a substantial ownership interest after these transactions.

Insider Trade Summary 10b5-1

Exercise and sale activity reported; no spread calculated

Exercise and Sale 8 txns

Insider Lewis William

Role Chair and CEO

Sold 25,564 shs ($2.72M)

Approx. gross sale proceeds $2.72M

Approx. exercise cost $267K

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	5,753	$105.32	$606K
Sale	Common Stock	11,836	$106.39	$1.26M
Sale	Common Stock	7,975	$106.97	$853K
holding	Common Stock	--	--	--

Holdings After Transaction: Stock Option (right to buy) — 42,797 contracts (Direct); Common Stock — 273,037 shares (Direct); Common Stock — 233,924 shares (Indirect, By trust)

Footnotes (5)

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 5,753 shares sold at prices ranging from $104.73 to $105.71 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 11,836 shares sold at prices ranging from $105.73 to $106.72 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 7,975 shares sold at prices ranging from $106.73 to $107.36 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. 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

Shares sold: 25,564 shares First sale price: $106.97 per share Second sale price: $106.39 per share +5 more

8 metrics

Shares sold 25,564 shares Total open-market sales on May 18, 2026

First sale price $106.97 per share Weighted average price for 7,975 shares sold

Second sale price $106.39 per share Weighted average price for 11,836 shares sold

Third sale price $105.32 per share Weighted average price for 5,753 shares sold

Options exercised 10,699 shares Total common shares from option exercises on May 18, 2026

Option strike price 1 $17.16 per share Exercise price for 4,440 stock options

Option strike price 2 $30.46 per share Exercise price for 6,259 stock options

Indirect trust holding 233,924 shares Common stock held indirectly by trust as of May 18, 2026

Key Terms

Rule 10b5-1 trading plan, weighted average sales price, Stock Option (right to buy), Common Stock, +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.

weighted average sales price financial

"This is the weighted average sales price representing 5,753 shares sold at prices ranging..."

Stock Option (right to buy) financial

"Stock Option (right to buy) ... underlying security title Common Stock..."

Common Stock financial

"security_title: Common Stock ... transaction_type: non-derivative"

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

vesting schedule financial

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

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 insider transactions did INSMED (INSM) CEO William Lewis report?

William Lewis reported open-market sales and option exercises in Insmed common stock. He sold 25,564 shares and exercised 10,699 stock options, reflecting a mix of liquidity-taking and continued equity exposure through direct and indirect holdings.

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

Lewis sold 25,564 Insmed shares in three open-market transactions. Weighted average prices ranged roughly from $104.73 to $107.36 per share, with each trade reported as a weighted average and detailed price ranges available upon request from the issuer or SEC staff.

What stock options did the INSMED (INSM) CEO exercise in this Form 4?

He exercised 10,699 stock options for Insmed common stock. The options had exercise prices of $17.16 and $30.46 per share, reflecting previously granted equity awards that had vested according to a stated multi-year vesting schedule described in the filing footnotes.

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

Yes. The filing states the transactions were effected under a Rule 10b5-1 trading plan. That plan was adopted on September 4, 2025, indicating these sales were pre-arranged rather than discretionary, which typically reduces the signaling value of their specific timing.

Does INSMED (INSM) CEO William Lewis still hold shares after these transactions?

Yes. The Form 4 shows ongoing direct holdings plus 233,924 shares held indirectly through a trust. While the filing details post-transaction share counts line by line, the overall disclosure indicates he retains a significant ownership stake in Insmed after the reported sales and exercises.

What does the vesting schedule note in the INSMED (INSM) Form 4 mean?

The vesting note explains that 25% of the options became exercisable on the first anniversary of the grant, with 12.5% vesting every six months thereafter through the fourth anniversary. This describes a typical multi-year incentive structure for executive compensation in stock options.

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

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Accepted by SEC EDGAR 05/20/2026 - 04:06 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)
05/18/2026

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	05/18/2026		M(1)		6,259	A	$30.46	294,161	D
Common Stock	05/18/2026		M(1)		4,440	A	$17.16	298,601	D
Common Stock	05/18/2026		S(1)		5,753	D	$105.32(2)	292,848	D
Common Stock	05/18/2026		S(1)		11,836	D	$106.39(3)	281,012	D
Common Stock	05/18/2026		S(1)		7,975	D	$106.97(4)	273,037	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	05/18/2026		M(1)			6,259	(5)	01/04/2028	Common Stock	6,259	$0	25,037	D
Stock Option (right to buy)	$17.16	05/18/2026		M(1)			4,440	(5)	05/17/2027	Common Stock	4,440	$0	17,760	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 5,753 shares sold at prices ranging from $104.73 to $105.71 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 11,836 shares sold at prices ranging from $105.73 to $106.72 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 7,975 shares sold at prices ranging from $106.73 to $107.36 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	05/20/2026
	** 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)