X0306 4 2014-02-14 0 0001484504 Gigamon Inc. GIMO 0001267021 DESIMONE DAVID ANTHONY C/O GIGAMON INC. 3300 OLCOTT STREET SANTA CLARA CA 95054 0 1 0 0 VP Engineering & Wwide Support Common Stock 2014-02-14 4 M 0 15759 12.42 A 80452 D Common Stock 2014-02-14 4 S 0 15759 30.6724 D 64693 D Common Stock 2014-02-15 4 F 0 1999 30.51 D 64194 D Stock Option (right to buy) 12.42 2014-02-14 4 M 0 15759 0.00 D 2022-11-05 Common Stock 15759 117574 D The sale price for this transaction reported in column 4 of Table I represents the weighted average sale price of the shares sold, ranging from $30.50 to $30.735 per share. Upon request by the Commission staff, the Issuer or a security holder of the Issuer, the Reporting Person will provide full information regarding the number of shares sold at each separate price. The reported shares were withheld to cover the Reporting Person's tax liability in connection with the vesting of restricted stock units, or RSUs. Includes shares acquired by the Reporting Person on February 18, 2014 pursuant to the Issuer's 2013 Employee Stock Purchase Plan. 25% of the shares underlying the option vest on October 8, 2013 and the remaining shares shall vest in 36 equal monthly installments thereafter. All share numbers and per share prices disclosed in this Form 4 give effect to the Issuer's one-for-three reverse stock split completed on May 20, 2013. /s/ Paul Shinn, Attorney-in-Fact 2014-02-19