X0306 4 2018-07-12 0 0001285819 OMEROS CORP OMER 0001472163 Kelbon Marcia S. 201 ELLIOTT AVENUE WEST SEATTLE WA 98119 0 1 0 0 VP Patent and General Counsel Common Stock 2018-07-12 4 M 0 4277 4.10 A 188922 D Common Stock 2018-07-12 4 S 0 4277 21.4838 D 184645 D Stock Option (Right to Buy) 4.10 2018-07-12 4 M 0 4277 0.00 D 2022-01-07 Common Stock 4277 83252 D Open market sale pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on September 8, 2017, and amended on May 17, 2018. The trading schedule, including sale periods, price and the number of shares to be sold, was established in accordance with Rule 10b5-1 under the Securities Exchange Act of 1934, as amended. This transaction was executed in multiple trades at prices ranging from $21.46 to $21.49; the price reported above reflects the weighted average sales price. The reporting person 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. The option vested and became exercisable over 48 equal monthly installments, with a vesting commencement date of April 1, 2011. /s/ Marcia S. Kelbon 2018-07-13