X0306 4 2016-05-23 0 0001419600 Flexion Therapeutics Inc FLXN 0001597407 Clayman Michael D. C/O FLEXION THERAPEUTICS, INC. 10 MALL ROAD, SUITE 301 BURLINGTON MA 01803 1 1 0 0 President and CEO Common Stock 2016-05-23 4 M 0 10369 0.1626 A 25722 D Common Stock 278661 I By the Michael D. Clayman 2006 Revocable Trust Common Stock 24600 I By the Michael D. Clayman Irrevocable Trust Common Stock 388683 I By Versant Development Fund III, Fund Stock option (right to buy) 0.1626 2016-05-23 4 M 0 10369 0.00 D 2019-09-23 Common Stock 10369 0 D Includes 1,785 shares of Common Stock that were acquired by the Reporting Person on May 20, 2016 at $8.92 per share pursuant to the Issuer's Employee Stock Purchase Plan. Shares held by Versant Development Fund III, LLC. The Reporting Person is a manager and minority member of Versant Development Fund III, LLC. The Reporting Person disclaims any beneficial ownership of the shares held by Versant Development Fund III, LLC except to the extent of his pecuniary interest in these shares. The stock option is fully vested and exercisable. /s/ Jonathan H. Mahlowitz, Attorney-in-Fact 2015-05-24