Shares of Denali Therapeutics Inc. /zigman2/quotes/200043077/composite DNLI +0.52% rocketed 29% into record territory in premarket trading Thursday, after Biogen Inc. /zigman2/quotes/201531540/composite BIIB -0.15% announced a $465 million equity investment as part of a collaboration on Denali's treatment for Parkinson's disease. Biogen's stock was little changed ahead of the open. Under terms of the collaboration, Biogen will make an upfront payment of $560 million, as well as the equity investment from the purchase of 13.3 million newly issued shares, representing about 11% of the shares outstanding, at $34.94 per share, which is 50% above Wednesday's closing price of $23.24. Denali will also be eligible to receive up to $1.125 billion in potential milestone payments depending on the achievement of certain development and commercial milestones. Biogen and Denali will co-develop and co-commercialize Denali's small molecule inhibitors of leucine-rich repeat kinase 2 (LRRK2) for Parkinson's, and Biogen will receive exclusive options to license two preclinical programs from Denali's transport vehicle (TV) technology platform. Denali's stock, which was on track to open above the June 3 record close of $28.82, has rallied 33.4% year to date through Wednesday, while Biogen shares have lost 6.9% and the S&P 500 /zigman2/quotes/210599714/realtime SPX +0.01% has gained 3.0%.