X0407 4 2023-06-07 0001701732 Altair Engineering Inc. ALTR 0001912935 Marraccini Jeffrey C/O ALTAIR ENGINEERING INC. 1820 E. BIG BEAVER RD. TROY MI 48083 1 See Remarks 0 Class A Common Stock 2023-06-07 4 M 0 2511 0 A 6513 D Class A Common Stock 2023-06-07 4 M 0 640 0 A 7153 D Class A Common Stock 2023-06-07 4 S 0 1379 74.607 D 5774 D Class A Common Stock 2023-06-07 4 S 0 1772 75.205 D 4002 D Stock Option (Right to Buy) 39.82 2023-06-07 4 M 0 2511 0 D 2030-06-02 Class A Common Stock 2511 2511 D Stock Option (Right to Buy) 5.18 2023-06-07 4 M 0 640 0 D 2027-06-09 Class A Common Stock 640 0 D Includes 3,256 Class A Common Stock restricted stock units that are unvested. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $74.00 to $74.995 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. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $75.00 to $75.49 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. The options vested in 2 equal annual installments commencing June 2, 2022. This option is currently fully vested. The options vested in 4 equal annual installments commencing June 9, 2018. This option is currently fully vested. /s/ Raoul Maitra, attorney-in-fact for Jeffrey Marraccini 2023-06-08