Regeneron director plans $340K stock sale

REGENERON PHARMACEUTICALS, INC.

Rhea-AI Filing Summary

REGENERON PHARMACEUTICALS, INC. (REGN) is named as the issuer in a Form 144 notice covering a proposed sale of its common stock by director Kathryn Guarini. The notice reports a planned sale of 400 shares of common stock on or after September 2, 2026, with an aggregate market value of $340,000, to be effected through UBS Financial Services Inc.

The shares are indicated as being issuable upon the exercise of a stock option on September 2, 2026, for cash. The filing also reports that Guarini sold 400 shares of Regeneron common stock on August 10, 2026, with an aggregate market value of $320,000, during the prior three months.

Key Figures

Shares proposed for sale: 400 shares Aggregate market value of proposed sale: $340,000 Date of proposed transaction: September 2, 2026 +3 more

6 metrics

Shares proposed for sale 400 shares Common stock covered by the Form 144 notice for September 2, 2026

Aggregate market value of proposed sale $340,000 Value listed for 400 Regeneron common shares in the Form 144 securities information

Date of proposed transaction September 2, 2026 Date tied to the 400-share sale and option exercise

Shares sold in prior 3 months 400 shares Regeneron common shares sold by Kathryn Guarini on August 10, 2026

Aggregate market value of prior sale $320,000 Value reported for the August 10, 2026 sale of 400 shares

Signature date February 13, 2026 Date accompanying the Form 144 signature by UBS Financial Services Inc. as attorney-in-fact

Key Terms

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

3 terms

Rule 144 regulatory

"See the 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

"Common | 09/02/2026 | Exercise of stock option | Issuer"

attorney-in-fact regulatory

"Signature | /s/ UBS Financial Services Inc., as attorney-in-fact for Kathryn"

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.

What does the Form 144 filing disclose for REGENERON PHARMACEUTICALS, INC. (REGN)?

It discloses that director Kathryn Guarini has filed a notice of proposed sale under Rule 144 for 400 shares of Regeneron common stock, with an aggregate market value of $340,000, expected on or after September 2, 2026.

How many REGN shares is Kathryn Guarini planning to sell under this Form 144?

The notice covers a proposed sale of 400 shares of Regeneron common stock. The filing lists an aggregate market value of approximately $340,000 for this block, to be transacted through UBS Financial Services Inc. on or after September 2, 2026.

How were the REGN shares in the new Form 144 to be obtained?

The 400 shares covered by the notice are stated as issuable upon the exercise of a stock option on September 2, 2026, for cash. The exercise is identified as the source of the securities to be sold by the director’s account.

What prior REGN stock sales by Kathryn Guarini are reported in the last three months?

The filing reports that Kathryn Guarini sold 400 shares of Regeneron common stock on August 10, 2026, with an aggregate market value of $320,000, as securities sold during the past three months.

Who is executing the proposed REGN share sale disclosed in the Form 144?

The proposed sale of 400 shares of Regeneron common stock is to be executed through UBS Financial Services Inc. at its New York office, as indicated in the securities information section of the Form 144 notice.

What exchange is referenced for the REGN shares in this Form 144?

The Form 144 lists the issuer’s common stock as traded on Nasdaq. The notice pertains specifically to Regeneron’s common shares planned for sale under Rule 144 by director Kathryn Guarini.

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

See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google

Add on Google Not now

Available on EDGAR 09/02/2026 - 04:10 PM EDT Accepted by SEC EDGAR 09/02/2026 - 04:09 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	340000.00	101137842	09/02/2026	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	09/02/2026	Exercise of stock option	Issuer			400	09/02/2026	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

144: Remarks and Signature

Remarks
Date of Notice	09/02/2026
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)