X0306 4 2015-05-15 0 0001484504 Gigamon Inc. GIMO 0001395697 Wilke Helmut C/O GIGAMON INC. 3300 OLCOTT STREET SANTA CLARA CA 95054 0 1 0 0 Sr VP Worldwide Sales Common Stock 2015-05-15 4 F 0 423 30.49 D 68660 D The reported shares were withheld to cover the Reporting Person's tax liability in connection with the vesting of restricted stock units. /s/ Paul Shinn, Attorney-in-Fact 2015-05-19