X0508 4 2024-10-23 0001701732 Altair Engineering Inc. ALTR 0001720807 Christ George J C/O ALTAIR ENGINEERING INC. 1820 E. BIG BEAVER RD. TROY MI 48083 1 0 Class A Common Stock 2024-10-23 4 S 0 2995 101.9199 D 97005 I By Christ Revocable Trust dated May 8, 2015 Class A Common Stock 2024-10-23 4 S 0 7040 103.0218 D 89965 I By Christ Revocable Trust dated May 8, 2015 Class A Common Stock 2024-10-23 4 S 0 1724 104.4948 D 88241 I By Christ Revocable Trust dated May 8, 2015 Class A Common Stock 2024-10-23 4 S 0 14545 106.5022 D 73696 I By Christ Revocable Trust dated May 8, 2015 Class A Common Stock 2024-10-23 4 S 0 69096 107.0794 D 4600 I By Christ Revocable Trust dated May 8, 2015 Class A Common Stock 2024-10-23 4 S 0 3601 108.2923 D 999 I By Christ Revocable Trust dated May 8, 2015 Class A Common Stock 2024-10-23 4 S 0 999 109.1316 D 0 I By Christ Revocable Trust dated May 8, 2015 Class A Common Stock 187475 I By The Dana Christ Irrevocable Trust Dated May 8, 2015 Class A Common Stock 187475 I By The Lauren Christ Irrevocable Trust Dated May 8, 2015 Class A Common Stock 300000 I By GC Investments LLC The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $101.35 to $102.24 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. Reporting person serves as Trustee. Reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of all of the reported shares for purposes of Section 16 or for any other purpose. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $102.50 to $103.41 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 price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $104.19 to $104.69 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 price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $105.77 to $106.765 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 price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $106.78 to $107.695 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 price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $107.86 to $108.85 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 price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $108.94 to $109.99 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. Reporting person serves as co-Trustee. Reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of all of the reported shares for purposes of Section 16 or for any other purpose. Reporting person serves as Manager. Reporting person disclaims beneficial ownership of these securities except to the extent of his pecuniary interest therein, and the inclusion of these shares in this report shall not be deemed an admission of beneficial ownership of all of the reported shares for purposes of Section 16 or for any other purpose. /s/ Raoul Maitra, attorney-in-fact for George J. Christ 2024-10-25