X0508 4 2025-12-04 0 0001805077 Eos Energy Enterprises, Inc. EOSE 0001782905 Walters Marian C/O EOS ENERGY ENTERPRISES, INC. 3920 PARK AVENUE EDISON NJ 08820 1 0 0 0 0 Common Stock 2025-12-04 4 M 0 18473 14.43 A 152267 D Common Stock 2025-12-04 4 F 0 16933 15.75 D 135334 D Common Stock 2025-12-04 4 M 0 50000 1.18 A 185334 D Common Stock 2025-12-04 4 S 0 50000 15.81 D 135334 D Common Stock 5000 I See footnote Stock Option (Right to Buy) 14.43 2025-12-04 4 M 0 18473 0 D 2025-12-08 Common Stock 18473 0 D Stock Option (Right to Buy) 1.18 2025-12-04 4 M 0 50000 0 D 2027-05-19 Common Stock 50000 95018 D The Reporting Person acquired shares through a cashless exercise transaction with the issuer in which the Reporting Person surrendered optioned shares in payment of the purchase price. These surrendered shares were sold in multiple transactions at prices ranging from $15.43 to $15.90, inclusive. The reporting person undertakes to provide the issuer, any security holder of the issuer, 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 range set forth above. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $15.42 to $16.02, inclusive. The reporting person undertakes to provide the issuer, any security holder of the issuer, 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 range set forth above. Shares of record held by David Walters and Marian Walters as trustees of the D. and M. Walters Family Trust dtd 7/6/2020. On December 8, 2020 the reporting person was granted stock options to purchase 18,473 shares of common stock which vested on June 15, 2021. On May 19, 2022 the reporting person was granted stock options to purchase 145,018 shares of common stock which vested on May 19, 2023. /s/ Michael Silberman as attorney-in-fact for Marian Walters 2025-12-08