Regeneron director Michael S. Brown proposes $1.58M sale

Morgan Stanley Smith Barney LLC is listed as broker, with NASDAQ identified as the exchange for the proposed sale.

Rhea-AI Filing Summary

Michael S. Brown, a director of Regeneron Pharmaceuticals, Inc. (REGN), reported a proposed sale of 1,929 common shares with an aggregate market value of $1,579,407.33. The approximate sale date is October 30, 2026; Morgan Stanley Smith Barney LLC is listed as broker and NASDAQ as the exchange. The securities are described as acquired from the issuer through exercise of stock options.

Key Figures

Common shares proposed for sale: 1,929 shares Aggregate market value: $1,579,407.33 Shares outstanding: 103,447,859 shares +1 more

4 metrics

Common shares proposed for sale 1,929 shares Approximate sale date: October 30, 2026

Aggregate market value $1,579,407.33 Proposed sale

Shares outstanding 103,447,859 shares Issuer securities information

Approximate sale date October 30, 2026 Proposed sale

Key Terms

Rule 144, Exercise of Stock Options

2 terms

Rule 144 regulatory

"definition of "person" in paragraph (a) of Rule 144"

Rule 144 is a U.S. securities regulation that sets conditions under which restricted or insider-held shares can be legally resold to the public, such as required holding periods, availability of public information, limits on how much can be sold at once, and certain filing requirements. For investors it matters because it determines when previously locked-up shares can enter the market — like a release valve that can increase supply, affect share price, and signal insider intent.

Exercise of Stock Options financial

"Exercise of Stock Options"

FAQ

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

How many REGN shares does Michael S. Brown propose to sell?

Michael S. Brown, a director of Regeneron Pharmaceuticals, Inc. (REGN), reported a proposed sale of 1,929 common shares with an aggregate market value of $1,579,407.33; the approximate sale date is October 30, 2026.

How were the REGN shares in Michael S. Brown’s proposed sale acquired?

The securities are described as acquired from the issuer through exercise of stock options. Morgan Stanley Smith Barney LLC is listed as broker, and NASDAQ as the exchange.

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

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Available on EDGAR 10/30/2026 - 04:21 PM EDT Accepted by SEC EDGAR 10/30/2026 - 04:20 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	0001174475
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	REGENERON PHARMACEUTICALS INC
SEC File Number	000-19034
Address of Issuer	777 Old Saw Mill River Road Tarrytown NEW YORK 10591
Phone	9148477000
Name of Person for Whose Account the Securities are To Be Sold	MICHAEL S BROWN
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	Director

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	Morgan Stanley Smith Barney LLC Executive Financial Services 1 New York Plaza 8th Floor New York NY 10004	1929	1579407.33	103447859	10/30/2026	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	10/30/2026	Exercise of Stock Options	Issuer			1929	10/30/2026	Cash

* 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

Nothing to Report

144: Remarks and Signature

Remarks
Date of Notice	10/30/2026
Date of Plan Adoption or Giving of Instruction, If Relying on Rule 10b5-1	02/25/2026
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	/s/ Michael S Brown
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)