X0306 4 2022-02-15 0001701732 Altair Engineering Inc. ALTR 0001762863 Messano Amy C/O ALTAIR ENGINEERING INC. 1820 E. BIG BEAVER RD. TROY MI 48083 1 Chief Marketing Officer Class A Common Stock 2022-02-15 4 A 0 2750 0 A 14114 D Class A Common Stock 2022-03-14 4 S 0 115 59.958 D 13603 D Stock Option (Right to Buy) 61.79 2022-02-15 4 A 0 8200 0 A 2032-02-15 Class A Common Stock 8200 8200 D On February 15, 2022, the Reporting Person was granted 2,750 Class A Common Stock restricted stock units, which vest in 4 equal annual installments commencing February 15, 2023. Includes 9,640 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 $59.86 to $59.96 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 9,249 Class A Common Stock restricted stock units that are unvested. On February 15, 2022, the Reporting Person was granted 8,200 Class A Common Stock options, the options vest in 4 equal annual installments commencing February 15, 2023. //s/ Raoul Maitra, attorney-in-fact for Amy Messano 2022-03-15