X0306 4/A 2013-02-25 2013-02-27 0 0000353569 QUIDEL CORP /DE/ QDEL 0001472036 Stenzel Timothy Todd 10165 MCKELLAR COURT SAN DIEGO CA 92121 0 1 0 0 Chief Science Officer Non-Qualified Stock Option 22.21 2013-02-25 4 A 0 24671 0.00 A 2023-02-25 Common Stock 24671 24671 D Restricted Stock Units 2013-02-25 4 A 0 1125 0.00 A Common Stock 1125 1125 D 12,336 shares will vest on the second anniversary date of the grant date, February 25, 2015. 6,168 shares will vest on the third anniversary date of the grant date, February 25, 2016. 6,167 shares will vest on the fourth anniversary date of the grant date, February 25, 2017. Each restricted stock unit represents the right to receive one share of Quidel Corporation common stock. 562 shares will vest on the second anniversary date of the grant date, February 25, 2015. 281 shares will vest on the third anniversary date of the grant date, February 25, 2016. 282 shares will vest on the fourth anniversary date of the grant date, February 25, 2017. This amended Form 4 is being filed to correct the number of derivative securities acquired by the reporting person, the related amount of securities underlying the derivative securities, and the amounts that vest on the respective vesting dates. Robert J. Bujarski, attorney-in-fact for Timothy T. Stenzel 2013-03-27