X0508 4 2026-01-12 0001285819 OMEROS CORP OMER 0002005787 Borges David J. 201 ELLIOTT AVENUE WEST SEATTLE WA 98119 1 VP, Finance & CAO 0 Common stock 2026-01-12 4 S 0 30000 12.72 D 0 D Common stock 2026-01-13 4 M 0 30000 3.06 A 30000 D Common stock 2026-01-13 4 S 0 30000 12.3105 D 0 D Stock Option (right to buy) 3.06 2026-01-13 4 M 0 30000 0 D 2034-04-25 Common Stock 30000 65000 D This transaction was executed in multiple trades at prices ranging from $12.56 to $13.06. The price reported above reflects the weighted average sales price. The reporting person hereby undertakes to provide full information regarding the number of shares and prices at which the transactions referenced in this footnote were effected upon request to the SEC staff, the issuer, or a security holder of the issuer. This transaction was executed in multiple trades at prices ranging from $12.13 to $12.62. The price reported above reflects the weighted average sales price. The reporting person hereby undertakes to provide full information regarding the number of shares and prices at which the transactions referenced in this footnote were effected upon request to the SEC staff, the issuer, or a security holder of the issuer. This option vests and becomes exercisable over 48 equal monthly installments, with a vesting commencement date of April 1, 2024. Installments vest and become exercisable on each monthly anniversary thereafter. The reporting person has completed all currently planned sales of Omeros Corporation's common stock. /s/ Peter B. Cancelmo, Attorney-in-Fact 2026-01-14