X0306 4 2021-01-08 0 0001305253 Eiger BioPharmaceuticals, Inc. EIGR 0001686952 Mayer Eldon C. III C/O EIGER BIOPHARMACEUTICALS, INC. 2155 PARK BOULEVARD PALO ALTO CA 94306 0 1 0 0 Ex VP & Chief Commerc. Officer Common Stock 2021-01-08 4 S 0 1690 11.68 D 35810 D These shares were sold by the reporting person to cover tax withholding obligations in connection with the vesting of the Restricted Stock Units granted on January 31, 2020 for 7,500 shares. /s/ Sriram Ryali, Attorney-in-Fact 2021-01-11