X0508 4 2025-03-03 0000944695 HANOVER INSURANCE GROUP, INC. THG 0001428157 Roche John C C/O THE HANOVER INSURANCE GROUP, INC. 440 LINCOLN STREET WORCESTER MA 01653 1 1 0 0 President and CEO 1 Common Stock 2025-03-03 4 M 0 10706 77.91 A 134983.851 D Common Stock 2025-03-03 4 S 0 1894 170.91 D 133089.851 D Common Stock 2025-03-03 4 S 0 3303 171.86 D 129786.851 D Common Stock 2025-03-03 4 S 0 5509 172.66 D 124277.851 D Common Stock Option (right to buy) 77.91 2025-03-03 4 M 0 10706 0 D 2026-02-23 Common Stock 10706 10707 D Exercise of options scheduled to expire in February 2025 and resulting sale of shares reported were effected pursuant to a pre-established Rule 10b5-1 Trading Plan adopted on November 5, 2024. Does not include 14,454 shares held by the Reporting Person's spouse. The price reported in Column 4 is a weighted average price. The shares were sold at multiple prices ranging from $170.33 to $171.33. 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 $171.34 to $172.34. 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 $172.35 to $173.31. 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 21,413 shares, vested 1/3 on each of 2/23/17, 2/23/18 and 2/23/19. /s/ Lindsay L. Katz pursuant to Confirming Statement 2025-03-04