X0306 4 2018-02-26 0 0000935494 NATIONAL INSTRUMENTS CORP NATI 0001008359 TRUCHARD JAMES J C/O NATIONAL INSTRUMENTS CORP 11500 N. MOPAC EXPRESSWAY AUSTIN TX 78759-3504 1 0 0 0 Common Stock 2018-02-26 4 S 0 67500 50.61 D 7752537 D Common Stock 2018-02-27 4 S 0 35000 50.53 D 7717537 D Common Stock 532372 I Held by Truchard Foundation, Dr. Truchard is the president. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on November 22, 2017. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $50.50 to $50.80, 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 to this Form 4. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $50.42 to $50.79, 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 to this Form 4. David G. Hugley as attorney-in-fact for James J. Truchard 2018-02-28