X0306 4 2016-08-12 0 0001285819 OMEROS CORP OMER 0001472158 Cable Thomas J. 201 ELLIOTT AVENUE WEST SEATTLE WA 98119 1 0 0 0 Common Stock 2016-08-12 4 S 0 3000 11.519 D 46067 D Open market sale pursuant to a Rule 10b5-1 trading plan adopted by the reporting person on May 19, 2016, at which time the trading schedule, including sale periods and the number of shares to be sold, was established in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended. This Rule 10b5-1 plan provides for fixed sales of a total of 9,000 shares over a one-year period beginning on August 12, 2016 and ending May 20, 2017, with sale periods commencing approximately every four months. This sale of 3,000 shares is the result of the first trade pursuant to this trading plan. This transaction was executed in multiple trades at prices ranging from $11.41 to $11.56; 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. /s/ Marcia S. Kelbon, attorney-in-fact on behalf of Thomas J. Cable 2016-08-16