Insmed (INSM) CEO sells shares, exercises options under 10b5-1 plan

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

Rhea-AI Filing Summary

Insmed Inc Chair and CEO William Lewis reported option exercises and share sales in Insmed common stock. On April 6, 2026, he exercised stock options for a total of 10,699 shares at strike prices of $30.46 and $17.16 per share, then sold 10,699 shares in open-market transactions at weighted average prices around $161.73, $163.23, and $164.01. These sales were carried out under a pre-arranged Rule 10b5-1 trading plan. After the transactions, he directly owned about 301,185 shares of common stock, with an additional 233,924 shares held indirectly through the Katie Procter Dynasty Trust.

Insider Trade Summary 10b5-1

Net Seller: 10,699 shares ($1,746,336)

Net Sell 8 txns

Insider Lewis William

Role Chair and CEO

Sold 10,699 shs ($1.75M)

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	787	$161.73	$127K
Sale	Common Stock	8,478	$163.23	$1.38M
Sale	Common Stock	1,434	$164.01	$235K
holding	Common Stock	--	--	--

Holdings After Transaction: Stock Option (right to buy) — 43,814 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 787 shares sold at prices ranging from $161.65 to $162.58 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 8,478 shares sold at prices ranging from $162.66 to $163.65 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 1,434 shares sold at prices ranging from $163.66 to $164.36 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. 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: 10,699 shares Sale price (block 1): $161.73 per share Sale price (block 2): $163.23 per share +5 more

8 metrics

Shares sold 10,699 shares Open-market sales of common stock on April 6, 2026

Sale price (block 1) $161.73 per share Weighted average price for 787 shares sold

Sale price (block 2) $163.23 per share Weighted average price for 8,478 shares sold

Sale price (block 3) $164.01 per share Weighted average price for 1,434 shares sold

Options exercised (strike $30.46) 6,259 shares Stock option exercise into common stock

Options exercised (strike $17.16) 4,440 shares Stock option exercise into common stock

Direct holdings after trades 301,185 shares Common stock directly owned after April 6, 2026 transactions

Indirect trust holdings 233,924 shares Held by the Katie Procter Dynasty Trust

Key Terms

Rule 10b5-1 trading plan, Stock Option (right to buy), weighted average sales price, open-market sale, +2 more

6 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 8,478 shares sold at prices..."

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.

derivative exercise/conversion financial

"transaction_action": "derivative exercise/conversion""

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.

Form 4 Insider Transactions: What Each Field Means →

04/08/2026 - 04:41 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

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)
04/06/2026

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)
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	04/06/2026		M⁽¹⁾		6,259	A	$30.46	307,444	D
Common Stock	04/06/2026		M⁽¹⁾		4,440	A	$17.16	311,884	D
Common Stock	04/06/2026		S⁽¹⁾		787	D	$161.73⁽²⁾	311,097	D
Common Stock	04/06/2026		S⁽¹⁾		8,478	D	$163.23⁽³⁾	302,619	D
Common Stock	04/06/2026		S⁽¹⁾		1,434	D	$164.01⁽⁴⁾	301,185	D
Common Stock								233,924	I	By the Katie Procter Dynasty 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	04/06/2026		M⁽¹⁾			6,259	⁽⁵⁾	01/04/2028	Common Stock	6,259	$0	43,814	D
Stock Option (right to buy)	$17.16	04/06/2026		M⁽¹⁾			4,440	⁽⁵⁾	05/17/2027	Common Stock	4,440	$0	31,080	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 787 shares sold at prices ranging from $161.65 to $162.58 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 8,478 shares sold at prices ranging from $162.66 to $163.65 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 1,434 shares sold at prices ranging from $163.66 to $164.36 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	04/08/2026
	** 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)

Source: View Original Filing on SEC EDGAR

FAQ

What insider transactions did INSM CEO William Lewis report on April 6, 2026?

William Lewis reported exercising options for 10,699 Insmed shares and selling 10,699 common shares in open-market trades on April 6, 2026. The filing shows both the option exercises and subsequent sales as part of his equity activity that day.

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

He sold a total of 10,699 Insmed common shares in three transactions at weighted average prices of about $161.73, $163.23, and $164.01 per share. Footnotes state each average covers sales within a narrow intraday price range.

What stock options did the INSM CEO exercise in this Form 4 filing?

The CEO exercised stock options to acquire 6,259 Insmed shares at a $30.46 strike price and 4,440 shares at a $17.16 strike price. These option grants vested over time under a schedule described in the filing’s vesting footnote.

How many 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 lists 233,924 additional shares held indirectly through the Katie Procter Dynasty Trust, reflecting a substantial ongoing ownership position.

Were the 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 pre-arranged plans schedule trades in advance to help separate them from short-term market timing decisions.