X0306 4 2015-11-18 0 0001285819 OMEROS CORP OMER 0001472158 Cable Thomas J. 201 ELLIOTT AVENUE WEST SEATTLE WA 98119 1 0 0 0 Common Stock 2015-11-18 4 S 0 2000 13.7346 D 51067 D Open market sale pursuant to a 10b5-1 trading plan adopted by the reporting person on November 21, 2014, 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 8,000 shares over a one-year period beginning March 2015, with sale periods commencing approximately every four months. This sale of 2,000 shares is the result of the third trade pursuant to this trading plan, which will end on March 31, 2016. This transaction was executed in multiple trades at prices ranging from $13.5966 to $13.98; 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 2015-11-20