X0303 4 2011-02-01 0 0000935494 NATIONAL INSTRUMENTS CORP /DE/ NATI 0001192884 HUGLEY DAVID C/O NATIONAL INSTRUMENTS CORP 11500 N. MOPAC, BLDG B AUSTIN TX 78759 0 1 0 0 VP & General Counsel Common Stock 2011-02-01 5 M 0 291 29.5545 A 21856 D Common Stock 2011-02-16 4 M 0 5517 20.12 A 27373 D Common Stock 2011-02-16 4 S 0 5517 48.1200 D 21856 D Employee Stock Option (right to buy) 20.1200 2011-02-16 4 M 0 5517 0 D 2013-04-16 Common Stock 7500 1983 D Acquisition of stock under Issuer's employee stock purchase plan. Options vested and became exercisable based on time and performance milestones set by the Issuer. David G. Hugley 2011-02-18