INSM insider/trustee sales include 129,805-share block; new 6,865-share Rule 144 filing

Rhea-AI Filing Summary

Insmed, Inc. (INSM) filed a Form 144 proposing the sale of 6,865 common shares under Rule 144, with an approximate aggregate market value of $881,244, to be sold through Merrill Lynch on NASDAQ on 08/18/2025. The filing states those shares were acquired on 08/18/2025 through stock plan activity and lists prior sales by the same account (William Lewis and William Lewis TTEE) totaling multiple transactions from 05/20/2025 through 08/04/2025, including a large sale of 129,805 shares on 06/16/2025 generating $13,027,678. The notice includes the standard Rule 144 attestation that the seller is not aware of undisclosed material adverse information.

Insights

Securities Analyst

TL;DR: Routine Rule 144 sale tied to stock-plan issuance; recent aggregated insider sales are notable but not conclusive.

The filing documents a planned sale of 6,865 shares acquired via a stock plan on the same date as the proposed sale, filed to comply with Rule 144. The historical sales log shows frequent dispositions by the same beneficial holder or trustee across May–August 2025, including a material block of 129,805 shares on 06/16/2025 that produced $13,027,678. These patterns can affect supply dynamics but the filing contains no financial results or forward-looking statements; impact appears neutral absent additional company context.

Corporate Governance / Risk Analyst

TL;DR: Multiple recent insider/trustee sales, including a large block, raise governance and signaling concerns.

The record of repeated sales by William Lewis and William Lewis TTEE within a short window, culminating in a large 129,805-share sale, could be viewed negatively by investors as insider liquidity events. The Form 144 shows the new 6,865-share sale stems from stock plan activity, but frequent dispositions by related parties warrant scrutiny of insider motivations and lock-up or plan schedules. The filing does not provide explanations or company disclosures to mitigate potential investor concerns.

Form 144 Filer Information	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 Form 144 NOTICE OF PROPOSED SALE OF SECURITIES PURSUANT TO RULE 144 UNDER THE SECURITIES ACT OF 1933
FORM 144

144: Filer Information

Filer CIK
Filer CCC
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer

SEC File Number

Address of Issuer

Phone

Name of Person for Whose Account the Securities are To Be Sold

See the definition of "person" in paragraph (a) of Rule 144. Information is to be given not only as to the person for whose account the securities are to be sold but also as to all other persons included in that definition. In addition, information shall be given as to sales by all persons whose sales are required by paragraph (e) of Rule 144 to be aggregated with sales for the account of the person filing this notice.

Relationship to Issuer

144: Securities Information

Title of the Class of Securities To Be Sold	Name and Address of the Broker	Number of Shares or Other Units To Be Sold	Aggregate Market Value	Number of Shares or Other Units Outstanding	Approximate Date of Sale	Name the Securities Exchange
Common	Merrill Lynch 1800 K ST NW Suite 800 Washington DC 20006	6865	881244.00	211374786	08/18/2025	NASDAQ

Furnish the following information with respect to the acquisition of the securities to be sold and with respect to the payment of all or any part of the purchase price or other consideration therefor:

144: Securities To Be Sold

Title of the Class	Date you Acquired	Nature of Acquisition Transaction	Name of Person from Whom Acquired	Is this a Gift?	Date Donor Acquired	Amount of Securities Acquired	Date of Payment	Nature of Payment *
Common	08/18/2025	Stock Plan Activity	Issuer			6865	08/18/2025	n/a

* If the securities were purchased and full payment therefor was not made in cash at the time of purchase, explain in the table or in a note thereto the nature of the consideration given. If the consideration consisted of any note or other obligation, or if payment was made in installments describe the arrangement and state when the note or other obligation was discharged in full or the last installment paid.

Furnish the following information as to all securities of the issuer sold during the past 3 months by the person for whose account the securities are to be sold.

144: Securities Sold During The Past 3 Months

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
William Lewis TTEE 700 US Highway 202/206 Bridgewater NJ 08807	Common	08/04/2025	6830	749801.00
William Lewis TTEE 700 US Highway 202/206 Bridgewater NJ 08807	Common	07/15/2025	6830	699036.00
William Lewis TTEE 700 US Highway 202/206 Bridgewater NJ 08807	Common	07/01/2025	6830	671409.00
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	06/16/2025	5204	521909.00
William Lewis TTEE 700 US Highway 202/206 Bridgewater NJ 08807	Common	06/16/2025	129805	13027678.00
William Lewis 700 US Highway 202/206 Bridgwater NJ 08807	Common	06/03/2025	5472	391248.00
William Lewis TTEE 700 US Highway 202/206 Bridgewater NJ 08807	Common	06/02/2025	6830	486834.00
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/20/2025	21057	1423819.00
William Lewis TTEE 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/20/2025	6830	462314.00

144: Remarks and Signature

Remarks

Date of Notice

Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1

ATTENTION:

The person for whose account the securities to which this notice relates are to be sold hereby represents by signing this notice that he does not know any material adverse information in regard to the current and prospective operations of the Issuer of the securities to be sold which has not been publicly disclosed. If such person has adopted a written trading plan or given trading instructions to satisfy Rule 10b5-1 under the Exchange Act, by signing the form and indicating the date that the plan was adopted or the instruction given, that person makes such representation as of the plan adoption or instruction date.

Signature

ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)