X0306 4 2018-10-08 0 0001419600 Flexion Therapeutics Inc FLXN 0001369453 Wentworth Kerry C/O FLEXION THERAPEUTICS, INC. 10 MALL ROAD, SUITE 301 BURLINGTON MA 01803 0 1 0 0 Chief Regulatory Officer Common Stock 2018-10-08 4 F 0 1002 18.60 D 11476 D Common Stock 6000 I By Spouse Represents shares withheld by the Issuer to satisfy income tax obligations associated with the vesting of a Restricted Stock Unit Award granted to the Reporting Person on February 1, 2018. /s/ Mark S. Levine, Attorney-in-Fact 2018-10-09