X0306 4 2018-10-18 1 0001305253 Eiger BioPharmaceuticals, Inc. EIGR 0001443898 INTERWEST PARTNERS X LP 2710 SAND HILL ROAD, SUITE 200 MENLO PARK CA 94025 0 0 1 0 0001460207 InterWest Management Partners X, LLC 2710 SAND HILL ROAD, SUITE 200 MENLO PARK CA 94025 0 0 1 0 0001293171 Kliman Gilbert H 2710 SAND HILL ROAD, SUITE 200 MENLO PARK CA 94025 0 0 1 0 0001207833 ORONSKY ARNOLD L 2710 SAND HILL ROAD, SUITE 200 MENLO PARK CA 94025 0 0 1 0 0001553019 Desai Keval 2710 SAND HILL ROAD, SUITE 200 MENLO PARK CA 94025 0 0 1 0 0001276600 NASR KHALED 2710 SAND HILL ROAD, SUITE 200 MENLO PARK CA 94025 0 0 1 0 Common Stock 2018-10-18 4 S 0 210800 12.0717 D 1388792 D Common Stock 2018-10-18 4 S 0 26465 12.001 D 1362327 D Price reflected is the weighted-average sale price for shares sold. The range of sale prices for the transactions reported was $12.00 to $12.30 per share. The Reporting Person undertakes to provide, upon request by the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price. Price reflected is the weighted-average sale price for shares sold. The range of sale prices for the transactions reported was $12.00 to $12.03 per share. The Reporting Person undertakes to provide, upon request by the SEC staff, the Issuer, or a security holder of the Issuer, full information regarding the number of shares sold at each separate price. These securities are held of record by InterWest Partners X, L.P. ("IW10"). InterWest Management Partners X, LLC ("IMP10") is the general partner of IW10 and has sole voting and investment control over the shares owned by IW10. Gilbert H. Kliman, and Arnold L. Oronsky are Managing Directors of IMP10 and, Keval Desai and Khaled A. Nasr, are Venture Members of IMP10. All Reporting Persons disclaim beneficial ownership of shares of Eiger BioPharmaceuticals, Inc. stock held by IW10, except to the extent of their respective pecuniary interest therein. The filing of this statement shall not be deemed an admission that, for purposes of Section 16 of the Securities Exchange Act of 1944, or otherwise, any of the Reporting Persons are the beneficial owner of all of the equity securities covered by this statement. /s/ Arnold L. Oronsky, Managing Director of InterWest Partners X, LP 2018-10-22 /s/ Arnold L. Oronsky, Managing Director of InterWest Management Partners X, L.L.C. 2018-10-22 /s/ Karen A. Wilson, Attorney-in-Fact for Gilbert H. Kliman 2018-10-22 /s/ Karen A. Wilson, Attorney-in-Fact for Arnold L. Oronsky 2018-10-22 /s/ Karen A. Wilson, Attorney-in-Fact for Keval Desai 2018-10-22 /s/ Karen A. Wilson, Attorney-in-Fact for Khaled A. Nasr 2018-10-22