X0306 4 2016-01-12 0 0000872589 REGENERON PHARMACEUTICALS INC REGN 0001121404 Sanofi 54, RUE LA BOETIE PARIS I0 75008 FRANCE 0 0 1 0 Common Stock 2016-01-12 4 P 0 5007 453.8912 A 23113577 I See note Common Stock 2016-01-12 4 P 0 2407 454.5971 A 23115984 I See note Common Stock 2016-01-12 4 P 0 2164 455.6774 A 23118148 I See note Common Stock 2016-01-12 4 P 0 3220 457.1844 A 23121368 I See note Common Stock 2016-01-12 4 P 0 3100 457.9952 A 23124468 I See note Common Stock 2016-01-12 4 P 0 2500 460.1156 A 23126968 I See note Common Stock 2016-01-12 4 P 0 3563 461.4128 A 23130531 I See note Common Stock 2016-01-12 4 P 0 4941 462.2263 A 23135472 I See note Common Stock 2016-01-12 4 P 0 2759 463.1723 A 23138231 I See note Common Stock 2016-01-12 4 P 0 4148 464.4110 A 23142379 I See note Common Stock 2016-01-12 4 P 0 8002 465.4998 A 23150381 I See note Common Stock 2016-01-12 4 P 0 3608 466.2618 A 23153989 I See note Common Stock 2016-01-12 4 P 0 4901 467.6617 A 23158890 I See note Common Stock 2016-01-12 4 P 0 5082 468.4646 A 23163972 I See note Common Stock 2016-01-12 4 P 0 14169 469.7058 A 23178141 I See note Common Stock 2016-01-12 4 P 0 7204 470.6444 A 23185345 I See note Common Stock 2016-01-12 4 P 0 3600 471.5617 A 23188945 I See note Common Stock 2016-01-12 4 P 0 3563 472.6410 A 23192508 I See note The number of securities reported represents an aggregate number of shares purchased in multiple market transactions over a range of purchase prices. The price reported represents the weighted average price per share. The Reporting Person undertakes to provide the staff of the SEC, the Issuer, or a stockholder of the Issuer, upon request, the number of shares purchased by the Reporting Person at each separate price within the range. Represents shares acquired directly by sanofi-aventis Amerique du Nord ("SAAN"). Purchase prices range from $453.09 to $454.07 per share, inclusive. Indirectly owned through (a) SAAN, a direct, wholly-owned subsidiary of Sanofi, and (b) Aventis Pharmaceuticals Inc. ("Aventis"), an indirect, wholly-owned subsidiary of SAAN. After giving effect to all acquisitions reported on this Form 4, the number of shares beneficially owned directly by SAAN and Aventis was 20,392,956 shares and 2,799,552 shares, respectively. Pursuant to the Amended and Restated Investor Agreement, dated as of January 11, 2014, by and among Sanofi, SAAN, sanofi-aventis US LLC, Aventis (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. Purchase prices range from $454.21 to $455.19 per share, inclusive. Purchase prices range from $455.24 to $456.19 per share, inclusive. Purchase prices range from $456.59 to $457.54 per share, inclusive. Purchase prices range from $457.60 to $458.41 per share, inclusive. Purchase prices range from $459.64 to $460.52 per share, inclusive. Purchase prices range from $460.71 to $461.66 per share, inclusive. Purchase prices range from $461.73 to $462.71 per share, inclusive. Purchase prices range from $462.83 to $463.46 per share, inclusive. Purchase prices range from $463.96 to $464.92 per share, inclusive. Purchase prices range from $464.99 to $465.93 per share, inclusive. Purchase prices range from $465.99 to $466.97 per share, inclusive. Purchase prices range from $466.99 to $467.94 per share, inclusive. Purchase prices range from $468.09 to $468.87 per share, inclusive. Purchase prices range from $469.11 to $470.10 per share, inclusive. Purchase prices range from $470.11 to $471.10 per share, inclusive. Purchase prices range from $471.14 to $471.92 per share, inclusive. Purchase prices range from $472.31 to $473.23 per share, inclusive. /s/ John Felitti, Associate Vice President, Corporate Law, Financial & Securities Law 2016-01-14