X0303 4 2011-05-01 0 0000935494 NATIONAL INSTRUMENTS CORP /DE/ NATI 0001362595 Hester Phillip D C/O NATIONAL INSTRUMENTS CORPORATION 11500 NORTH MOPAC AUSTIN TX 78759 0 1 0 0 Senior Vice President Common Stock 2011-05-02 4 M 0 7514 A 7514 D Common Stock 2011-05-02 4 F 0 1988 30.32 D 5526 D Restricted Stock Units 2011-05-01 4 M 0 7514 0 D 2024-05-01 Common Stock 45000 37486 D Each restricted stock unit represents a contingent right to receive one share of the Issuer's common stock. The restricted stock units vest and become exercisable based on time and performance milestones set by the Issuer. On February 22, 2011, the common stock of National Instruments Corporation split 3-for-2, resulting in the reporting person's ownership of additional shares of common stock. David G. Hugley as attorney-in-fact for Phillip D. Hester 2011-05-03