X0306 4 2015-07-01 0 0000709283 QUANTUM CORP /DE/ QTM 0001517455 Clark Robert S. C/O QUANTUM CORPORATION 224 AIRPORT PARKWAY, SUITE 300 SAN JOSE CA 95110 0 1 0 0 SVP, Product Operations Common Stock 2015-07-01 4 A 0 160000 0.00 A 856485 D Common Stock 2015-07-01 4 A 0 51000 0.00 A 907485 D Common Stock 2015-07-01 4 F 0 101521 1.69 D 805964 D Restricted stock units will vest in equal installments on 07/01/2016, 07/01/2017, 07/01/2018 and 07/01/2019. Grant of performance stock units of which 17,000 vested on July 1, 2015 and 17,000 will vest on each of July 1, 2016 and July 1, 2017. Surrender of shares to satisfy tax withholding obligations upon vesting of restricted stock units granted on 7/1/2012,7/1/2013 and on 7/1/2014 and upon vesting of performance stock units granted on 7/1/2014. Astrid Becker-Celik, Attorney in Fact for Robert S. Clark 2015-07-02