Insmed Form 4: Chief Legal Officer trims 2.5% stake via 10b5-1 plan

Rhea-AI Filing Summary

Insmed Inc. (INSM) Form 4 filing discloses two open-market sales by Chief Legal Officer Michael A. Smith.

• 07/11/2025: 748 common shares sold at $96.41 to satisfy tax-withholding on RSU vesting.
• 07/15/2025: 933 common shares sold at a $102.51 weighted-average price under a pre-arranged Rule 10b5-1 trading plan adopted 02/27/2025.
• Total shares disposed: 1,681, representing roughly 2.5 % of his pre-sale direct holdings.
• Post-sale direct ownership: 66,394 shares, including 357 acquired via the 2018 ESPP.

No derivative transactions were reported. Sales appear routine and transparent, suggesting limited immediate valuation impact for investors.

Positive

• Transparent 10b5-1 plan disclosure reinforces good governance practices.
• Executive retains a large 66,394-share stake, maintaining alignment with shareholders.

Negative

• Insider selling, even if modest, can be perceived as a bearish signal by some investors.

Insights

Securities Analyst

TL;DR: Small 10b5-1 insider sale; negligible strategic signal.

The sales involve under 1,700 shares, only ~2.5 % of Mr. Smith’s stake. Because one trade covers tax withholding on RSU vesting and the other follows a pre-scheduled 10b5-1 plan, the activity looks administrative rather than opportunistic. Post-sale ownership remains substantial, implying ongoing alignment with shareholders. From a market-impact standpoint, the transactions are immaterial relative to INSM’s ~100 M share float and daily volume, so I rate the filing as neutral.

Corporate Governance Expert

TL;DR: Transparent compliance; governance practices intact.

The inclusion of Rule 10b5-1 details and explicit tax-withholding explanation demonstrates good disclosure hygiene. No red flags emerge regarding timing or volume. The executive continues to own >66 k shares, preserving a meaningful economic stake. Consequently, this filing neither enhances nor detracts from Insmed’s governance profile. Impact for investors is not material.

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).

1. Name and Address of Reporting Person^*

Smith Michael Alexander

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Legal Officer

3. Date of Earliest Transaction (Month/Day/Year)
07/11/2025

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	07/11/2025		S(1)		748	D	$96.41	67,327(2)	D
Common Stock	07/15/2025		S(3)		933	D	$102.51(4)	66,394	D

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

Explanation of Responses:

1. Shares sold to satisfy tax withholding obligations upon the vesting of Restricted Stock Units and to cover related broker fees.

2. Includes 357 shares acquired through the Company's 2018 Employee Stock Purchase Plan.

3. This transaction was effected pursuant to a 10b5-1 trading plan adopted by the Reporting Person on February 27, 2025, in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended.

4. This is the weighted average sales price representing 933 shares sold at prices ranging from $102.37 to $102.70 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.

Remarks:

	/s/ Michael A. Smith	07/15/2025
	** 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

How many INSM shares did the executive sell?

Michael A. Smith sold 1,681 common shares across two transactions.

What prices were the INSM shares sold at?

Shares were sold at $96.41 on 07/11/25 and at a weighted-average $102.51 on 07/15/25.

Why were the shares sold?

748 shares were sold to cover tax withholding on RSU vesting; 933 shares were sold under a Rule 10b5-1 plan.

How many INSM shares does Michael A. Smith now own?

After the transactions, he directly owns 66,394 common shares.

Does this Form 4 filing impact Insmed's outlook?

The modest, pre-scheduled sales are viewed as neutral and not expected to affect Insmed’s fundamental outlook.