X0609 4 2026-05-19 0 0001805077 Eos Energy Enterprises, Inc. EOSE 0001782905 Walters Marian false C/O EOS ENERGY ENTERPRISES, INC. 3920 PARK AVENUE EDISON NJ 08820 1 0 0 0 0 Common Stock 2026-05-19 4 M 0 7681 1.18 A 143015 D Common Stock 2026-05-19 4 S 0 7681 7.07 D 135334 D Common Stock 2026-05-19 4 M 0 23111 0 A 158445 D Common Stock 5000 I See footnote Restricted Stock Units 2026-05-19 4 M 0 23111 0 D Common Stock 23111 0 D Stock Option (Right to Buy) 1.18 2026-05-19 4 M 0 7681 0 D 2027-05-19 Common Stock 7681 87337 D The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $7.01 to $7.24, 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. Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock. Shares of records held by David Walters and Marian Walters as trustees of the D. and M. Walters Family Trust dtd 7/6/2020 Not applicable. 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. 50,000 of these stock options were previously exercised on December 4, 2025. /s/ Michael Silberman as attorney-in-fact for Marian Walters 2026-05-19