X0508 4 2025-05-07 0000944695 HANOVER INSURANCE GROUP, INC. THG 0001709075 Salvatore Bryan J C/O THE HANOVER INSURANCE GROUP, INC. 440 LINCOLN STREET WORCESTER MA 01653 0 1 0 0 Executive Vice President 1 Common Stock 2025-05-07 4 M 0 10526 82.39 A 36389.588 D Common Stock 2025-05-07 4 S 0 4975 166.12 D 31414.588 D Common Stock 2025-05-07 4 S 0 5437 167.01 D 25977.588 D Common Stock 2025-05-07 4 S 0 114 167.76 D 25863.588 D Common Stock Option (right to buy) 82.39 2025-05-07 4 M 0 10526 0 D 2027-06-12 Common Stock 10526 0 D Exercise of options scheduled to expire in June 2027 and resulting sale of shares reported were effected pursuant to a pre-established Rule 10b5-1 Trading Plan adopted on November 27, 2024. The price reported in Column 4 is a weighted average price. The shares were sold at multiple prices ranging from $165.60 to $166.59. The Reporting Person undertakes to provide The Hanover Insurance Group, Inc. ("THG"), any security holder of THG, or the staff of the SEC, upon request, full information regarding the number of shares sold at each separate price within the range set forth above. The price reported in Column 4 is a weighted average price. The shares were sold at multiple prices ranging from $166.63 to $167.56. The Reporting Person undertakes to provide THG, any security holder of THG, or the staff of the SEC, upon request, full information regarding the number of shares sold at each separate price within the range set forth above. The price reported in Column 4 is a weighted average price. The shares were sold at multiple prices ranging from $167.61 to $167.78. The Reporting Person undertakes to provide THG, any security holder of THG, or the staff of the SEC, upon request, full information regarding the number of shares sold at each separate price within the range set forth above. The option, representing the right to purchase a total of 21,052 shares, vested 1/3 on each of 6/12/2018, 6/12/2019 and 6/12/2020. /s/ Lindsay L. Katz pursuant to Confirming Statement 2025-05-08