X0306 4 2022-01-14 0 0001701732 Altair Engineering Inc. ALTR 0001762863 Messano Amy C/O ALTAIR ENGINEERING INC. 1820 E. BIG BEAVER RD. TROY MI 48083 0 1 0 0 Chief Marketing Officer Class A Common Stock 2022-01-14 4 A 0 109 54.57 A 11364 D Shares purchased under the Altair Engineering Inc. 2021 Employee Stock Purchase Plan in a transaction exempt under Rule 16b-3(c). Includes 6,890 Class A Common Stock restricted stock units that are unvested. /s/ Raoul Maitra, attorney-in-fact for Amy Messano 2022-01-19