Regeneron director proposes $360K share sale

The notice also lists two earlier 400-share sales by Guarini during the preceding three months.

Rhea-AI Filing Summary

Regeneron Pharmaceuticals, Inc. (REGN) director Kathryn Guarini submitted notice of a proposed sale of 400 common shares, with an aggregate market value of $360,000. The notice lists an approximate sale date of October 30, 2026, through UBS Financial Services, Inc., on Nasdaq. The shares are listed as acquired through exercise of a stock option from the issuer, with cash payment. During the prior three months, Guarini reported sales of 400 shares on August 10, 2026, for $320,000, and 400 shares on September 2, 2026, for $340,000.

Key Figures

Proposed shares for sale: 400 shares Aggregate market value: $360,000 Shares sold: 400 shares +3 more

6 metrics

Proposed shares for sale 400 shares Approximate sale date October 30, 2026

Aggregate market value $360,000 Proposed sale

Shares sold 400 shares August 10, 2026

Gross proceeds $320,000 Sale on August 10, 2026

Shares sold 400 shares September 2, 2026

Gross proceeds $340,000 Sale on September 2, 2026

Key Terms

Rule 144, Exercise of stock option, attorney-in-fact

3 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 option financial

"Exercise of stock option"

attorney-in-fact technical

"as attorney-in-fact for Kathryn Guarini"

An attorney-in-fact is the person or entity given legal authority through a power of attorney to act on behalf of another for specific tasks, such as signing documents, voting shares, or handling transactions. For investors, this matters because it lets a trusted representative make timely decisions or complete paperwork when the owner cannot, much like handing keys to someone to run errands on your behalf—so checks on scope and limits of that authority are important.

FAQ

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

How many REGN shares does Kathryn Guarini plan to sell?

Kathryn Guarini proposed to sell 400 common shares, with an aggregate market value of $360,000. The notice gives an approximate sale date of October 30, 2026, and lists UBS Financial Services, Inc. as the broker and Nasdaq as the exchange.

What REGN shares did Kathryn Guarini sell in the prior three months?

Kathryn Guarini reported sales of 400 shares on August 10, 2026, for $320,000, and 400 shares on September 2, 2026, for $340,000. The notice lists these transactions in its prior-three-month sales section.

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

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Available on EDGAR 10/30/2026 - 04:15 PM EDT Accepted by SEC EDGAR 10/30/2026 - 04:15 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	0001992352
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	Guarini Kathryn
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	UBS Financial Services, Inc. Eleven Madison Avenue 4th Floor New York NY 10010	400	360000.00	101630713	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 option	Issuer			400	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

Name and Address of Seller	Title of Securities Sold	Date of Sale	Amount of Securities Sold	Gross Proceeds
Kathryn Guarini 777 OLD SAW MILL RIVER ROAD TARRYTOWN NY 10591	Common	08/10/2026	400	320000.00
Kathryn Guarini 777 OLD SAW MILL RIVER ROAD TARRYTOWN NY 10591	Common	09/02/2026	400	340000.00

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	02/13/2026
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/ UBS Financial Services Inc., as attorney-in-fact for Kathryn Guarini
ATTENTION: Intentional misstatements or omission of facts constitute Federal Criminal Violations (See 18 U.S.C. 1001)