INSM Form 4: William Lewis Exercises 6,865 Options and Executes 10b5-1 Sales

Rhea-AI Filing Summary

Insmed Inc. insider transactions by Chair and CEO William Lewis show option exercises and multiple stock sales executed under a 10b5-1 plan on 08/18/2025. The filing reports the exercise of 6,865 stock options at an exercise price of $10.85 and the acquisition of 6,865 common shares via that exercise. On the same date the reporting person sold a total of 6,865 common shares in separate sell transactions: 2,968 shares at a weighted average price of $127.59, 2,481 shares at $128.76, and 1,416 shares at $129.47. After these transactions the reporting person beneficially owns 303,911 shares indirectly and 50,500 shares indirectly via two trusts.

Positive

• Transactions executed under a documented 10b5-1 plan, indicating pre-planned and rule-compliant insider sales.
• Options exercised at $10.85 converting to 6,865 shares, illustrating intrinsic value capture versus exercise price.

Negative

• Insider sold 6,865 shares on 08/18/2025, reducing holdings via three sell blocks (2,968; 2,481; 1,416 shares).
• Reported sales at high market prices may be perceived as insider monetization rather than vote of confidence in near-term upside.

Insights

Corporate Governance Expert

TL;DR: Option exercise followed by plan-led share sales is routine insider liquidity, disclosed under a pre-existing 10b5-1 plan.

The Form 4 indicates the reporting person adopted a 10b5-1 trading plan on September 12, 2024, and executed transactions on August 18, 2025 pursuant to that plan. The disclosure shows option exercises converting to 6,865 shares and contemporaneous open-market sales of the same aggregate amount across three sale blocks at weighted average prices between $127.59 and $129.47. The filing includes clear pricing ranges and an undertaking to provide per-price breakdowns on request, which supports compliance and transparency. Impact is procedural rather than operational.

Securities/Equity Analyst

TL;DR: Insider monetized equity via exercised options and market sales; remaining indirect holdings remain sizeable.

The report shows an exercise price of $10.85 for 6,865 options that became exercisable and were exercised on 08/18/2025. Proceeds were partially realized by selling those shares in three blocks totaling 6,865 shares at weighted average sale prices of $127.59, $128.76, and $129.47. Post-transactions beneficial ownership is reported as 303,911 shares (indirect) plus 50,500 shares (indirect by another trust). For investors, this is a liquidity event by an insider rather than new information about company performance.

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
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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)
08/18/2025

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	08/18/2025		M(1)		6,865	A	$10.85	240,789	I	By the Katie Procter Dynasty Trust
Common Stock	08/18/2025		S(1)		2,968	D	$127.59(2)	237,821	I	By the Katie Procter Dynasty Trust
Common Stock	08/18/2025		S(1)		2,481	D	$128.76(3)	235,340	I	By the Katie Procter Dynasty Trust
Common Stock	08/18/2025		S(1)		1,416	D	$129.47(4)	233,924	I	By the Katie Procter Dynasty Trust
Common Stock								303,911	D
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)	$10.85	08/18/2025		M(1)			6,865	(5)	05/19/2026	Common Stock	6,865	$0	0	I	By the Katie Procter Dynasty Trust

Explanation of Responses:

1. This transaction was effected pursuant to a 10b5-1 trading plan adopted by the Reporting Person on September 12, 2024, in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended.

2. This is the weighted average sales price representing 2,968 shares sold at prices ranging from $127.20 to $128.16 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 2,481 shares sold at prices ranging from $128.26 to $129.21 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 1,416 shares sold at prices ranging from $129.26 to $129.95 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. All options are currently exercisable.

Remarks:

Exhibit List - Exhibit 24 - Power of Attorney

	/s/ William Lewis, by Michael A. Smith as Attorney-in-fact	08/20/2025
	** 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 insider transactions did INSM Chair and CEO William Lewis report on Form 4?

The Form 4 reports the exercise of 6,865 stock options at $10.85 and sales of 6,865 common shares on 08/18/2025 under a 10b5-1 plan.

How many shares did William Lewis sell and at what prices?

He sold 2,968 shares at a weighted average price of $127.59, 2,481 shares at $128.76, and 1,416 shares at $129.47 on 08/18/2025.

What is William Lewis's beneficial ownership after the transactions?

The filing reports indirect beneficial ownership of 303,911 shares and 50,500 shares held indirectly by the William Lewis Family Legacy Trust.

Were these transactions part of a pre-arranged trading plan?

Yes. The filing states the transactions were effected pursuant to a 10b5-1 trading plan adopted by the reporting person on September 12, 2024.

When did the options become exercisable?

The filing states all options are currently exercisable and notes a vesting schedule: 25% after one year and 12.5% every six months thereafter until four years.