X0609 4 2026-06-26 0 0001805077 Eos Energy Enterprises, Inc. EOSE 0001991521 Puri Sumeet false C/O EOS ENERGY ENTERPRISES, INC. 3920 PARK AVENUE EDISON NJ 08820 0 1 0 0 Chief Accounting Officer 1 Common Stock 2026-06-26 4 M 0 17645 0 A 181935 D Common Stock 2026-06-30 4 S 0 8823 5.86 D 173112 D Restricted Stock Units 2026-06-26 4 M 0 17545 0 D Common Stock 17545 35389 D Each restricted stock unit ("RSU") represents a contingent right to receive one share of common stock. The sales reported in this Form 4 were effected automatically pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 12, 2025 to cover estimated tax withholding obligations in connection with the vesting of restricted stock units. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $5.68 to $6.12, 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 reporting person received a grant of RSUs under the Issuer's 2020 Incentive Plan, which will vest in three equal installments on each of the first three anniversaries of the grant date, subject to continued service through each vesting date. Not applicable. /s/ Michael Silberman as attorney-in-fact for Sumeet Puri 2026-06-30