X0609 4 2026-04-21 0001710340 Eton Pharmaceuticals, Inc. ETON 0001161662 RIEDEL NORBERT G false C/O ETON PHARMACEUTICALS, INC. 21925 W. FIELD PARKWAY, SUITE 235 DEERPARK IL 60010-7208 1 0 Common Stock 2026-04-21 4 M 0 12500 7.31 A 47500 D Common Stock 2026-04-21 4 M 0 19655 8.61 A 67155 D Common Stock 157145 I By Trust Employee Stock Option (Right to Buy) 7.31 2026-04-21 4 M 0 12500 0 D 2020-02-20 2029-02-19 Common Stock 12500 0 D Employee Stock Option (Right to Buy) 8.61 2026-04-21 4 M 0 19655 0 D 2022-05-03 2031-05-02 Common Stock 19655 0 D Shares held in 'Norbert. G. Riedel 2002 Trust, Loan Thi Tran 2002 Trust' family trust, as to which the Reporting Person is a trustee. The reporting person has authorized and designated the named person to file this Form 4 on the reporting person's behalf for indefinite duration. /s/ James R. Gruber 2026-04-22