Insmed (INSM) legal chief sells 6,149 shares under Rule 10b5-1 plan

Rhea-AI Filing Summary

INSMED Inc Chief Legal Officer Michael Alexander Smith reported an open-market sale of 6,149 shares of common stock at $108.47 per share. The transaction was made under a pre-arranged Rule 10b5-1 trading plan adopted on November 7, 2025. Following this sale, he directly holds 41,613 company shares.

Insider Trade Summary 10b5-1

Net Seller: 6,149 shares ($666,982)

Net Sell 1 txn

Insider Smith Michael Alexander

Role Chief Legal Officer

Sold 6,149 shs ($667K)

Type	Security	Shares	Price	Value
Sale	Common Stock	6,149	$108.47	$667K

Holdings After Transaction: Common Stock — 41,613 shares (Direct, null)

Footnotes (1)

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Key Figures

Shares sold: 6,149 shares Sale price: $108.47 per share Shares held after transaction: 41,613 shares +1 more

4 metrics

Shares sold 6,149 shares Open-market sale on May 22, 2026

Sale price $108.47 per share Common Stock transaction

Shares held after transaction 41,613 shares Direct ownership following sale

Sell transactions count 1 transaction Net-sell activity in this Form 4

Key Terms

Rule 10b5-1 trading plan, open-market sale, Securities Exchange Act of 1934

3 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.

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.

Securities Exchange Act of 1934 regulatory

"in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended"

Form 4 Insider Transactions: What Each Field Means →

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^*

Smith Michael Alexander

(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)

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/22/2026

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	05/22/2026		S(1)		6,149	D	$108.47	41,613	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. This transaction was effected pursuant to a 10b5-1 trading plan adopted by the Reporting Person on November 7, 2025, in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended.

Remarks:

	/s/ Michael A. Smith	05/22/2026
	** 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)

FAQ

What insider transaction did INSMED (INSM) report for Michael Alexander Smith?

Michael Alexander Smith sold 6,149 INSMED shares in the open market. The sale involved common stock at $108.47 per share, and was executed under a pre-arranged Rule 10b5-1 trading plan adopted on November 7, 2025.

At what price were the INSMED (INSM) shares sold in this Form 4 filing?

The reported sale price was $108.47 per INSMED share. Chief Legal Officer Michael Alexander Smith sold 6,149 shares of common stock at this price in an open-market transaction disclosed in the Form 4 insider trading report.

How many INSMED (INSM) shares does Michael Alexander Smith hold after the sale?

After the reported sale, Smith directly holds 41,613 INSMED shares. The Form 4 indicates that his direct ownership position declined by 6,149 shares as a result of the open-market transaction executed under a Rule 10b5-1 trading plan.

Was the INSMED (INSM) insider sale made under a Rule 10b5-1 plan?

Yes, the sale was executed under a Rule 10b5-1 trading plan. The footnote explains that the transaction followed a pre-arranged plan adopted on November 7, 2025, established in accordance with Rule 10b5-1 of the Exchange Act.

What role does Michael Alexander Smith hold at INSMED (INSM)?

Michael Alexander Smith serves as INSMED’s Chief Legal Officer. The Form 4 identifies him as an executive officer and shows his direct open-market sale of 6,149 common shares and his remaining direct ownership of 41,613 shares after the transaction.