INSM Form 144: William Lewis reports planned sale of 25,564 shares

INSM reported proposed sales of common stock under a Form 144 notice by William Lewis.

Rhea-AI Filing Summary

INSM reported proposed sales of common stock under a Form 144 notice by William Lewis. The excerpt lists multiple sale dates and share amounts, including 25,564 shares on 05/18/2026, 13,283 shares on 05/13/2026 and several transactions of 10,699 shares between 03/05/2026 and 05/04/2026.

These entries appear as stock plan activity and individual dispositions; timing and cash‑flow counterparties are not described in the provided excerpt.

Insights

Securities Attorney

Routine Form 144 notice listing proposed insider dispositions.

The filing lists multiple proposed sales by William Lewis with specific share counts and dates, consistent with a Form 144 disclosure of intended distributions or sales. The entries include 25,564 shares on 05/18/2026 and prior dispositions of 13,283 and 10,699 shares.

These rows reflect reported transactions or plan-related distributions; the excerpt does not state whether sales were executed, the method of sale, or receiving parties. Subsequent transaction confirmations would appear in trade reports or Form 4 filings.

Corporate Governance Analyst

Multiple small-to-moderate insider disposals over a short period.

The pattern shows repeated dispositions from 03/05/2026 through 05/18/2026, mostly in 10,699 share increments and one larger 25,564 entry. The excerpt labels one row as "Stock Plan Activity" dated 06/01/2026.

Without post‑transaction holdings confirmation or Form 4 trade reports in this excerpt, proportionality to total holdings cannot be assessed here; filings that follow may provide the full position picture.

Key Figures

Largest reported sale: 25,564 shares Notable sale: 13,283 shares Repeated sale size: 10,699 shares +2 more

5 metrics

Largest reported sale 25,564 shares Sale dated 05/18/2026

Notable sale 13,283 shares Sale dated 05/13/2026

Repeated sale size 10,699 shares Multiple dates between 03/05/2026 and 05/04/2026

Stock Plan Activity line 7605 Entry labeled "Stock Plan Activity" dated 06/01/2026

Form type Form 144 Filed format for proposed sales notice

Key Terms

Form 144, Stock Plan Activity, Issuer

3 terms

Form 144 regulatory

"Repeated as the filing type and disclosure mechanism for proposed sales"

Form 144 is a document that investors must file with the government when they plan to sell a large number of shares of a company's stock. It helps ensure transparency so everyone knows how many shares are being sold and when, which can impact the stock's price.

Stock Plan Activity financial

"One row labeled "Stock Plan Activity" dated 06/01/2026"

Issuer regulatory

"Row showing "Issuer" in the Securities To Be Sold section"

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What does the INSM Form 144 entry mean for William Lewis?

It reports proposed or realized sales of INSM common shares by William Lewis. The excerpt lists specific sale dates and share counts for multiple transactions, such as 25,564 shares on 05/18/2026 and earlier sales of 13,283 and 10,699 shares.

Does the excerpt show the proceeds or buyers for the sales (INSM)?

No—this excerpt does not state proceeds or counterparties for the sales. It provides sale dates and share quantities but does not describe sale prices, receiving parties, or how cash flowed from the transactions.

Are these transactions listed as stock plan activity or open‑market sales for INSM?

The excerpt includes both labels: one line is marked "Stock Plan Activity" dated 06/01/2026, while other rows list individual dispositions by William Lewis on specified dates. The method of sale for each row is not detailed.

Will Form 144 alone confirm whether the insider actually sold the shares?

Form 144 notifies of proposed sales but does not by itself confirm settlement. Execution and settlement details typically appear in trade reporting or subsequent Form 4 filings; those are not included in this excerpt.

How many shares were reported sold in the largest entry shown for INSM?

The largest single entry in the provided excerpt is 25,564 shares on 05/18/2026. Several other entries list 10,699 shares and one lists 13,283 shares on earlier dates.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 06/03/2026 - 04:10 PM EDT Learn about SEC filing dates

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	0001402051
Filer CCC	XXXXXXXX
Is this a LIVE or TEST Filing?	LIVE TEST
Submission Contact Information
Name
Phone
E-Mail Address

144: Issuer Information

Name of Issuer	INSMED INC
SEC File Number	000-30739
Address of Issuer	700 US Highway 202/206 Bridgewater NEW JERSEY 08807
Phone	9089779900
Name of Person for Whose Account the Securities are To Be Sold	William Lewis
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	Officer

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	7605	777763	216752451	06/03/2026	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	06/01/2026	Stock Plan Activity	Issuer			7605	06/01/2026	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 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/18/2026	25564	2718106
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/13/2026	13283	1543186
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	05/04/2026	10699	1469434
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	04/16/2026	10699	1540292
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	04/06/2026	10699	1746319
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	03/19/2026	10699	1535514
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	03/05/2026	10699	1562311

144: Remarks and Signature

Remarks
Date of Notice	06/03/2026
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	William Lewis
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)