Certain Warrants of Portola Pharmaceuticals, Inc. are subject to a Lock-Up Agreement Ending on 12-NOV-2019. These Warrants will be under lockup for 91 days starting from 13-AUG-2019 to 12-NOV-2019. Details: The directors and executive officers have agreed not to offer, pledge, sell, contract to sell, sell any option or contract to purchase, purchase any option or contract to sell, grant any option, right or warrant to purchase, lend or otherwise transfer or dispose of, directly or indirectly, any shares of common stock or any securities convertible into or exercisable or exchangeable for shares of common stock for a period of 90 days after the date of this prospectus supplement.