Certain Restricted Stock Units of Ra Pharmaceuticals, Inc. are subject to a Lock-Up Agreement Ending on 24-AUG-2019. These Restricted Stock Units will be under lockup for 31 days starting from 24-JUL-2019 to 24-AUG-2019. Details: The company officers and directors and certain other stockholders have agreed that they will not offer, sell, contract to sell, pledge or otherwise dispose of, directly or indirectly, any shares of its common stock or securities convertible into or exchangeable or exercisable for any shares of its common stock for a period of 30 days after the date of this prospectus supplement.