X0306 4 2015-05-01 0 0000935494 NATIONAL INSTRUMENTS CORP /DE/ NATI 0001574827 Starkloff Eric Howard C/O NATIONAL INSTRUMENTS CORPORATION 11500 NORTH MOPAC AUSTIN TX 78759 0 1 0 0 Executive Vice President Common Stock 2015-05-01 5 M 0 382 24.3100 A 6661 D Common Stock 2015-05-01 4 M 0 6595 A 13256 D Common Stock 2015-05-01 4 F 0 1834 28.3406 D 11422 D Restricted Stock Units 2015-05-01 4 M 0 3 0 D 2021-05-01 Common Stock 3 0 D Restricted Stock Units 2015-05-01 4 M 0 845 0 D 2022-05-01 Common Stock 966 121 D Restricted Stock Units 2015-05-01 4 M 0 845 0 D 2023-05-01 Common Stock 1926 1081 D Restricted Stock Units 2015-05-01 4 M 0 676 0 D 2024-05-01 Common Stock 2267 1591 D Restricted Stock Units 2015-05-01 4 M 0 845 0 D 2026-05-01 Common Stock 4834 3989 D Restricted Stock Units 2015-05-01 4 M 0 845 0 D 2027-05-01 Common Stock 5864 5019 D Restricted Stock Units 2015-05-01 4 M 0 845 0 D 2028-05-01 Common Stock 6733 5888 D Restricted Stock Units 2015-05-01 4 M 0 1691 0 D 2029-05-01 Common Stock 15000 13309 D Acquisition of stock under Issuer's employee stock purchase plan. 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. David G. Hugley as attorney-in-fact for Eric H. Starkloff 2015-05-05