EXHIBIT A

JOINT FILING AGREEMENT

The undersigned hereby agree that the statement on Schedule 13G with respect to the Common Stock of Eiger BioPharmaceuticals, Inc. dated as of October 15, 2018 is, and any further amendments thereto signed by each of the undersigned shall be, filed on behalf of each of the undersigned pursuant to and in accordance with the provisions of Rule 13d-1(k)(2) under the Securities Exchange Act of 1934, as amended.

Dated: October 15, 2018

683 CAPITAL MANAGEMENT, LLC

By:  /s/ Ari Zweiman             Ari Zweiman,            Authorized Person

683 CAPITAL PARTNERS, LP

By:  /s/ Ari Zweiman             Ari Zweiman,            Authorized Person

/s/ Ari Zweiman
     ARI ZWEIMAN