INSM Form 144: William Lewis lists proposed stock sales

INSM filed a Form 144 reporting proposed sales of Common Stock by William Lewis.

Rhea-AI Filing Summary

INSM filed a Form 144 reporting proposed sales of Common Stock by William Lewis. The notice lists multiple proposed dispositions with trade dates and share counts, for example 13,283 shares on 05/13/2026 and 10,699 shares on 05/04/2026. The entries also show large associated position figures on each line.

Insights

Securities Counsel

Form 144 lists proposed resale transactions by an affiliated holder; this is a regulatory notice, not proof of execution.

Form 144 is a notice of proposed sales by an affiliate under Rule 144. The excerpt shows multiple dated entries and share counts attributed to William Lewis, which document intended dispositions and related position figures on each line.

Timing and whether sales were completed are not stated in the excerpt; subsequent filings or broker confirmations would show settlement. Future public filings may report actual executed transactions.

Key Figures

Proposed sale: 13,283 shares Proposed sale: 10,699 shares Proposed sale: 10,699 shares +3 more

6 metrics

Proposed sale 13,283 shares 05/13/2026 entry

Proposed sale 10,699 shares 05/04/2026 entry (also repeated on other dates)

Proposed sale 10,699 shares 04/16/2026 entry

Associated position figure 1,543,186 Shown on 05/13/2026 line

Associated position figure 1,469,434 Shown on 05/04/2026 line

Associated position figure 1,540,292 Shown on 04/16/2026 line

Key Terms

Form 144, Stock Plan Activity, Common

3 terms

Form 144 regulatory

"144: Securities Sold During The Past 3 Months"

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

"05/18/2026 | Stock Plan Activity | Issuer"

Common financial

"Common | 05/18/2026 | Stock Plan Activity"

FAQ

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

What does the INSM Form 144 disclose about William Lewis's activity?

The Form 144 discloses proposed sales of Common Stock by William Lewis. It lists dated entries such as 13,283 shares on 05/13/2026 and 10,699 shares on 05/04/2026, along with associated position figures.

Does the Form 144 prove the shares were sold for INSM (symbol INSM)?

No. Form 144 indicates proposed or planned sales by an affiliate; it does not confirm execution. The excerpt shows proposed trade dates and quantities but does not state whether transactions settled.

Which dates and share counts are shown in the INSM excerpt?

The excerpt includes multiple dates and counts, for example 05/13/2026: 13,283 shares and 05/04/2026: 10,699 shares. Several additional dates in March and April 2026 show recurring 10,699-share entries.

Who is the reporting person named in the INSM Form 144 excerpt?

The reporting person named throughout the excerpt is William Lewis, with the address line shown as 700 US Highway 202/206, Bridgewater NJ 08807, tied to multiple dated entries.

Do the numbers after each sale date indicate remaining holdings in the excerpt?

The excerpt shows a second numeric column on each line (e.g., 1,543,186) adjacent to the sale counts. The excerpt presents these figures but does not label them explicitly within the provided text.

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

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Accepted by SEC EDGAR 05/18/2026 - 04:53 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	25564	2718106	216752451	05/18/2026	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	05/18/2026	Stock Plan Activity	Issuer			10699	05/18/2026	n/a
Common	05/11/2026	Stock Plan Activity	Issuer			14865	05/11/2026	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	05/13/2026	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
William Lewis 700 US Highway 202/206 Bridgewater NJ 08807	Common	02/19/2026	10699	1615250

144: Remarks and Signature

Remarks
Date of Notice	05/18/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	09/04/2025
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)