144 0001991521 XXXXXXXX LIVE 0001805077 Eos Energy Enterprises, Inc. 001-39291 3920 PARK AVENUE EDISON NJ 08820 (732) 225-8400 Puri Sumeet Officer Common UBS Financial Services Inc.

11 Madison Avenue 4th Floor New York NY 10010

20501 143006.78 259853606 09/08/2025 Nasdaq Common UBS Fincial Services Inc.

11 Madison Ave 4th Floor New York NY 10010

20000 145062.00 259853606 09/08/2025 Nasdaq Common 09/05/2025 RSU Vesting Issuer N 40501 09/05/2025 NA N Sumeet Puri

3920 Park Avenue Edison NJ 08820

Common 07/29/2025 17500 103880.00 The 20,501 shares reported on this Form 144 will be sold pursuant to a Rule 10b5-1 trading plan adopted by the reporting person to cover estimated tax withholding obligations from the vesting of restricted stock units. The 20,000 shares reported represents a sale by the reporting person to satisfy estimated tax liabilities arising from vesting of restricted stock units on July 25, 2025 and September 5, 2025, to the extent the estimated tax liabilities exceeded the amount sold on July 29, 2025 and September 8, 2025 pursuant to the Rule 10b5-1 trading plan adopted by the reporting person on March 14, 2025. 09/08/2025 03/14/2025 /s/ UBS Financial Services Inc, as attorney-in-fact for Sumeet Puri