X0306 4 2013-02-15 0 0001012140 ONYX PHARMACEUTICALS INC ONXX 0001312622 Foster-Cheek Kaye I C/O ONYX PHARMACEUTICALS, INC. 249 E. GRAND AVE. SOUTH SAN FRANCISCO CA 94080 0 1 0 0 SVP, Global Human Resources Common Stock 2013-02-15 4 M 0 3184 37.68 A 28683 D Common Stock 2013-02-15 4 M 0 9480 26.38 A 38163 D Common Stock 2013-02-15 4 M 0 3500 35.18 A 41663 D Common Stock 2013-02-15 4 S 0 16164 74.96 D 25499 D Stock Option (right to Buy) 37.68 2013-02-15 4 M 0 3184 0.00 D 2022-03-29 Common Stock 3184 30241 D Stock Option (Right to Buy) 26.38 2013-02-15 4 M 0 9480 0.00 D 2020-09-30 Common Stock 9480 42312 D Stock Option (Right to Buy) 35.18 2013-02-15 4 M 0 3500 0.00 D 2021-03-31 Common Stock 3500 15167 D The shares were sold pursuant to a 10b5-1 plan. 12.5% of the shares subject to the option became exercisable 6 months following the date of grant. The remaining shares become exercisable in equal monthly installments over the following 42 months for a total vesting schedule of 48 months. Twenty-Five percent of the shares subject to the option vest and become exercisable one year from the date of grant and vest and become exercisable at a rate of 1/48th per month thereafter. The shares were sold at prices ranging from $74.90 to $75.00. The reporting person will provide upon request to the SEC, the issuer or security holder of the issuer, full information regarding the number of shares sold to each separate price. /s/ Warren DeSouza, Attorney-in-fact 2013-02-20