X0306 4 2020-12-04 0 0001701732 Altair Engineering Inc. ALTR 0001720665 Dagg James C/O ALTAIR ENGINEERING INC. 1820 E. BIG BEAVER ROAD TROY MI 48083 0 1 0 0 See Remarks Class A Common Stock 2020-12-04 4 M 0 8000 0.00 A 14054 D Class A Common Stock 2020-12-04 4 S 0 8000 52.875 D 6054 D Stock Option (right to buy) 0.00 2020-12-04 4 M 0 8000 0.00 D 2036-12-01 Class A Common Stock 8000 576452 D The option exercise price is $0.000025. Includes 4,515 Class A Common Stock restricted stock units that are unvested. The sale of the shares of Class A Common Stock were made pursuant to a plan intended to comply with Rule 10b5-1 of the Exchange Act, previously entered into on March 5, 2020. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $52.27 to $53.095 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 upon grant. The option is currently fully vested. Chief Technical Officer, Modeling/Visualization /s/ Raoul Maitra, attorney-in-fact for James Dagg 2020-12-08