X0306 4 2022-03-14 0001701732 Altair Engineering Inc. ALTR 0001912935 Marraccini Jeffrey C/O ALTAIR ENGINEERING INC. 1820 E. BIG BEAVER RD. TROY MI 48083 1 See Remarks Class A Common Stock 2022-03-14 4 S 0 126 59.963 D 2471 D The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $59.96 to $60.21 per share, inclusive. The reporting person undertakes to provide to Altair Engineering Inc., any security holder of Altair Engineering Inc., 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 herein. Includes 2,127 Class A Common Stock restricted stock units that are unvested. Chief Information Security Officer /s/ Raoul Maitra, attorney-in-fact for Jeffrey Marraccini 2022-03-15