X0609 4 2026-05-22 0001710340 Eton Pharmaceuticals, Inc. ETON 0001968254 Krempa David false C/O ETON PHARMACEUTICALS, INC. 21925 W. FIELD PARKWAY, SUITE 235 DEERPARK IL 60010-7208 1 Chief Business Officer 0 Common Stock 2026-05-22 4 M 0 30591 3.58 A 68046 D Common Stock 2026-05-22 4 S 0 32963 33.2208 D 35083 D Common Stock 2026-05-22 4 S 0 9315 33.8802 D 25768 D Common Stock 2026-05-22 4 S 0 519 35 D 25249 D Common Stock 2026-05-26 4 M 0 25000 1.38 A 50249 D Common Stock 2026-05-26 4 M 0 12524 1.37 A 62773 D Common Stock 2026-05-26 4 S 0 37524 31.4927 D 25249 D Common Stock 2026-05-27 4 M 0 12476 1.37 A 37725 D Common Stock 2026-05-27 4 M 0 7203 3.58 A 44928 D Common Stock 2026-05-27 4 S 0 19679 31.4739 D 25249 D Employee Stock Option 3.58 2026-05-22 4 M 0 30591 0 D 2020-03-12 2030-03-11 Common Stock 30591 125609 D Employee Stock Option 1.38 2026-05-26 4 M 0 25000 0 D 2017-08-07 2027-08-06 Common Stock 25000 0 D Employee Stock Option 1.37 2026-05-26 4 M 0 12524 0 D 2017-11-10 2027-11-09 Common Stock 12524 12476 D Employee Stock Option 1.37 2026-05-27 4 M 0 12476 0 D 2017-11-10 2027-11-09 Common Stock 12476 0 D Employee Stock Option 3.58 2026-05-27 4 M 0 7203 0 D 2020-03-12 2030-03-11 Common Stock 7203 118406 D The Reporting Person will provide upon request by the Securities and Exchange Commission staff, the issuer, or a security holder of the issuer, full information regarding the number of shares sold at each separate price. The shares were sold in multiple trades at prices ranging from $33.68 to $34.66. The price reported above reflects the weighted average sales price. The shares were sold in multiple trades at prices ranging from $31.27 to $32.16. The price reported above reflects the weighted average sales price. The shares subject to the option vested in 48 equal monthly installments from the date of grant (3-12-2020) until fully vested. The shares were sold in multiple trades at prices ranging from $31.25 to $31.825. The price reported above reflects the weighted average sales price. The shares subject to the option vested annually from the date of grant (11-10-2017) in four equal installments. The shares were sold in multiple trades at prices ranging from $32.67 to $33.65. The price reported above reflects the weighted average sales price. The shares subject to option vested annually from the date of grant (8-7-2017) in four equal installments. 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/ Judith Matthews 2026-05-27