 Shares of Perrigo Co. gained 0.8 in premarket trading on Wednesday, after the company disclosed in a financial filing that it will not receive a 400 million milestone payment based on 2020 sales of multiple sclerosis drug Tysabri. Perrigo announced in 2017 that it would divest its royalty rights for Tysabri to the privately held Royalty Pharma for 2.2 billion in cash and up to 650 million in potential milestone payments. 