X0306 4 2015-07-02 0 0001594864 Juno Therapeutics, Inc. JUNO 0001281933 BRATTON DOUGLAS K 201 MAIN STREET, SUITE 1900 FORT WORTH TX 76102 0 0 1 0 Common Stock 2015-07-02 4 S 0 40000 54.75 D 182669 I By JT Line Partners LP Common Stock 25766130 I By CL Alaska, L.P. The price reported in Column 4 is a weighted average price. These shares reported as sold on July 2, 2015 were sold in multiple transactions at prices ranging from a low of $54.00 per share to a high of $55.64 per share. The reporting person undertakes to provide to Juno Therapeutics, Inc. ("Issuer"), any security holder of the Issuer or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price set forth above. The shares of the Issuer reported in Column 5 are held directly by JT Line Partners LP ("JT"). The general partner of JT is Bratton Capital Management L.P. ("Bratton Capital Management"). The general partner of Bratton Capital Management is Bratton Capital, Inc. ("Bratton Capital"). Douglas K. Bratton is the sole director of Bratton Capital. JT is ultimately controlled by Mr. Bratton and Mr. Bratton has voting and investment power over all of the shares of the Issuer held by JT, as well as a partial pecuniary interest in such shares. JT directly beneficially owns these shares of the Issuer. Bratton Capital Management, Bratton Capital and Mr. Bratton may each be deemed to indirectly beneficially own the shares of the Issuer held by JT. Each such entity and Mr. Bratton disclaims beneficial ownership of these shares, except to the extent of its or his respective pecuniary interest therein. These 25,766,130 shares of the Issuer are held directly by CL Alaska, L.P. ("CLA"). The general partner of CLA is Crestline SI (GP), L.P. ("Crestline SI") and the investment manager of CLA is Crestline Management, L.P. ("Crestline Management"). Crestline Investors, Inc. ("Crestline") is the general partner of both Crestline SI and Crestline Management. Douglas K. Bratton is the sole director of Crestline. CLA is ultimately controlled by Mr. Bratton and Mr. Bratton has voting and investment power over all of these shares of the Issuer, as well as a partial pecuniary interest in the shares held by CLA. Mr. Bratton does not intend to sell shares of the Issuer from CLA at this time, however, please see the related disclosures in Item 4 of the Schedule 13D/A filed on June 25, 2015. CLA may be deemed to directly beneficially own all of these shares of the Issuer. (Continued from Footnote 3) Crestline SI, Crestline Management, Crestline and Mr. Bratton may each be deemed to indirectly beneficially own all of these shares of the Issuer. Each such entity and Mr. Bratton disclaims beneficial ownership of these shares, except to the extent of its or his respective pecuniary interest therein. /s/ Douglas K. Bratton 2015-07-02