X0306 4 2020-03-09 0000872589 REGENERON PHARMACEUTICALS, INC. REGN 0001121404 Sanofi 54 RUE LA BOETIE PARIS I0 75008 FRANCE true Common Stock 2020-03-09 4 S 0 128914 489.6532 D 20421899 D Common Stock 2799552 I See note Private sale to the Issuer pursuant to the letter agreement entered into with the Issuer on January 7, 2018 and filed on January 9, 2018 by the Reporting Person as Exhibit 99.4 to Amendment No. 13 to Reporting Person's statement on Schedule 13D. Directly owned by Aventisub LLC ("Aventisub"), formerly known as Aventis Pharmaceuticals Inc., an indirect, wholly-owned subsidiary of the Reporting Person. Pursuant to the Amended and Restated Investor Agreement, dated as of January 11, 2014, by and among the Reporting Person, sanofi-aventis US LLC, Aventis, sanofi-aventis Amerique du Nord (collectively, the "Sanofi Parties") and the Issuer, the Sanofi Parties have agreed to vote their respective shares of the Issuer, subject to specified exceptions, in accordance with the recommendation of the Issuer's Board of Directors. Exhibit 24 - Power of Attorney (incorporated herein by reference to Exhibit 24 to Form 4 filed by the Reporting Person with the SEC on February 3, 2016, with respect to Alnylam Pharmaceuticals, Inc.). /s/ Alexandra Roger Name: Alexandra Roger Title: Attorney-in-fact 2020-03-11