X0306 4 2018-05-01 0 0000935494 NATIONAL INSTRUMENTS CORP NATI 0001598818 Rust Scott Arthur C/O NATIONAL INSTRUMENTS CORPORATION 11500 NORTH MOPAC AUSTIN TX 78759 0 1 0 0 Senior Vice President Common Stock 2018-05-01 5 M 0 216 34.7565 A 29738 D Common Stock 2018-05-01 4 M 0 11528 A 41266 D Common Stock 2018-05-01 4 F 0 2869 40.0676 D 38397 D Restricted Stock Units 2018-05-01 4 M 0 391 0 D 2024-05-01 Common Stock 391 0 D Restricted Stock Units 2018-05-01 4 M 0 830 0 D 2026-05-01 Common Stock 830 1659 D Restricted Stock Units 2018-05-01 4 M 0 775 0 D 2027-05-01 Common Stock 775 2509 D Restricted Stock Units 2018-05-01 4 M 0 498 0 D 2028-05-01 Common Stock 498 2135 D Restricted Stock Units 2018-05-01 4 M 0 553 0 D 2029-05-01 Common Stock 553 2883 D Restricted Stock Units 2018-05-01 4 M 0 1660 0 D 2030-05-01 Common Stock 1660 10340 D Restricted Stock Units 2018-05-01 4 M 0 1821 0 D 2031-05-01 Common Stock 1821 11679 D Restricted Stock Units 2018-05-01 4 M 0 5000 0 D 2032-05-01 Common Stock 5000 15000 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. The restricted stock units vest in four equal annual installments on the anniversary of the vesting commencement date of May 1, 2017. David G. Hugley as attorney-in-fact for Scott Arthur Rust 2018-05-03