X0306 4 2017-12-28 0 0001285819 OMEROS CORP OMER 0001472160 Demopulos Gregory A MD 201 ELLIOTT AVENUE WEST SEATTLE WA 98119 1 1 0 0 Chairman, CEO & President Common Stock 2017-12-28 4 M 0 102040 2.45 A 1987025 D Common Stock 2017-12-28 4 M 0 39961 4.10 A 2026986 D Stock Option (Right to Buy) 2.45 2017-12-28 4 M 0 102040 0.00 D 2017-12-29 Common Stock 102040 0 D Stock Option (Right to Buy) 4.10 2017-12-28 4 M 0 39961 0.00 D 2022-01-08 Common Stock 39961 220039 D On December 28, 2017, the reporting person paid the exercise price and exercised expiring non-qualified stock options to purchase 102,040 shares of the company's common stock. These shares have not been sold and are held for the account of the reporting person. One-fourth of the shares subject to this option vested on December 30, 2008, which was the first anniversary of the grant date, and the remainder became exercisable in equal monthly installments over the following 48 months. In addition to paying the exercise price of the expiring non-qualified stock options, the reporting person is concurrently paying ordinary income taxes incurred as a result of the exercise of these options. On December 28, 2017, the reporting person paid the exercise price and exercised incentive stock options to purchase 39,961 shares of the company's common stock. These shares have not been sold and are held for the account of the reporting person. This option vested and became exercisable in 48 equal monthly installments. The first installment became exercisable on April 1, 2011 and subsequent installments became exercisable on each monthly anniversary thereafter. /s/ Marcia S. Kelbon, attorney in-fact on behalf of Gegory A. Demopulos 2017-12-28