X0306 4 2019-03-15 0001701732 Altair Engineering Inc. ALTR 0001720314 Scapa James Ralph C/O ALTAIR ENGINEERING INC. 1820 E. BIG BEAVER RD. TROY MI 48083 1 1 1 Chief Executive Officer Class A Common Stock 2019-03-15 4 A 0 965 0 A 965 I By wife Class A Common Stock 2020-03-11 4 A 0 896 0 A 1861 I By wife Class A Common Stock 2020-03-17 4 S 0 85 24.614 D 1776 I By wife Class A Common Stock 2021-03-12 4 S 0 77 59.45 D 1699 I By wife Class A Common Stock 2021-03-12 4 S 0 4 60.54 D 1695 I By wife Class A Common Stock 2021-03-15 4 A 0 83 0 A 1778 I By wife Class A Common Stock 2021-03-16 4 S 0 1 59.39 D 1777 I By wife Class A Common Stock 2021-03-16 4 S 0 83 60.43 D 1694 I By wife Class A Common Stock 2022-03-14 4 S 0 92 59.959 D 1602 I By wife Class A Common Stock 2022-03-16 4 S 0 106 58.48 D 1496 I By wife Class A Common Stock 2022-03-16 4 S 0 1 59.86 D 1495 I By wife Class A Common Stock 2022-03-16 4 M 0 19305 0 A 138029 D Class A Common Stock 2022-03-16 4 S 0 1738 58.48 D 136291 D Class A Common Stock 2022-03-16 4 S 0 22 59.99 D 136269 D Stock Option (Right to Buy) 5.18 2022-03-16 4 M 0 19305 0 D 2027-06-09 Class A Common Stock 19305 10695 D On March 15, 2019, the Reporting Person's wife was granted 965 Class A Common Stock restricted stock units, which vest in 4 equal annual installments commencing March 15, 2020. Includes 965 Class A Common Stock restricted stock units that are unvested. On March 11, 2020, the Reporting Person's wife was granted 863 Class A Common Stock restricted stock units, which vest in 4 equal annual installments commencing March 11, 2021. Includes 1,861 Class A Common Stock restricted stock units that are unvested. Includes 1,620 Class A Common Stock restricted stock units that are unvested. Includes 1,396 Class A Common Stock restricted stock units that are unvested. On March 15, 2021, the Reporting Person's wife was granted 83 Class A Common Stock restricted stock units, which vest in 4 equal annual installments commencing March 15, 2022. Includes 1,238 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 $59.91 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 1,014 Class A Common Stock restricted stock units that are unvested. Includes 752 Class A Common Stock restricted stock units that are unvested. Includes 33,000 Class A Common Stock restricted stock units that are unvested. The options vest in 4 equal annual installments commencing June 9, 2018. /s/ Raoul Maitra, attorney-in-fact for James R. Scapa 2022-03-18