X0306 4 2014-05-13 0 0001503802 Karyopharm Therapeutics Inc. KPTI 0001603510 Primiano Christopher Brett C/O KARYOPHARM THERAPEUTICS INC., 2 MERCER ROAD NATICK MA 01760 0 1 0 0 VP, GEN COUNSEL & SECRETARY Common Stock 2014-05-13 4 P 0 1000 26.75 A 1000 D The price reported in Column 4 is a weighted average price. These shares were purchased in multiple transactions at prices ranging from $26.4999 to $27.00, inclusive. The reporting person undertakes to provide to Karyopharm Therapeutics Inc., any security holder of Karyopharm Therapeutics Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the ranges set forth in footnote (1) to this Form 4. /s/ Christopher B. Primiano 2014-05-13