X0306 4 2021-06-04 1 0001701732 Altair Engineering Inc. ALTR 0001720664 Kowal Jan C/O ALTAIR ENGINEERING INC. 1820 E. BIG BEAVER RD. TROY MI 48083 1 Class A Common Stock 2021-06-04 4 M 0 4000 5.18 A 13000 D Class A Common Stock 2021-06-04 4 S 0 4000 66.696 D 9000 D Stock Option (Right to Buy) 5.18 2021-06-04 4 M 0 4000 0 D 2027-06-09 Class A Common Stock 4000 0 D The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $66.60 to $66.82 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 option becomes exercisable as to 50% of the shares on June 9, 2018 and the remaining shares vest on June 9, 2019. This option is currently fully vested. /s/ Raoul Maitra, attorney-in-fact for Jan Kowal 2021-06-07