Shares of Vir Biotechnology Inc. /zigman2/quotes/214486077/composite VIR -3.77% were up 12.8% in premarket trading on Wednesday after the company said it would expand its research agreement with GlaxoSmithKline /zigman2/quotes/209463850/composite GSK +0.52% to include the flu and other respiratory diseases. As part of the deal, GSK will pay Vir $225 million upfront and will make an equity investment of $120 million in the biotech; it also has the option to develop one drug for $300 million, with the possibility of an additional $200 million in milestone payments. The companies had initially engaged in a deal in 2020 that is focused on studying treatments for coronaviruses, including SARS-CoV-2. One experimental COVID-19 treatment that the companies are already developing is VIR-7831, which is being tested in Phase 3 studies as a monotherapy and in a mid-stage trial as a combination therapy. Vir's stock has soared 287.7% over the past 12 months, while the broader S&P 500 /zigman2/quotes/210599714/realtime SPX +0.77% is up 16.%.