X0306 4 2015-08-03 0 0000935494 NATIONAL INSTRUMENTS CORP /DE/ 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 2015-08-03 5 M 0 250 24.3100 A 31465.5 D Common Stock 2015-11-02 4 S 0 3262.5 30.6803 D 28203 D Acquisition of stock under Issuer's employee stock purchase plan. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $30.6801 to $30.6812, inclusive. The reporting person undertakes to provide to National Instruments Corporation, any security holder of National Instruments Corporation or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote. David G. Hugley as attorney-in-fact for Scott Arthur Rust 2015-11-02