ARS Technica has some more info about his later life:
With this newfound wealth he created his own investment firm, Vulcan Inc. One funding priority has been space; he helped fund the Allen Telescope Array in California, and in 2011 he created Stratolaunch, a space company that wants to launch rockets from a giant airplane. Local sports were also a priority; Allen bought the Seattle Seahawks NFL team in 1996 to prevent it from being moved to California, and he was a minority owner of the Seattle Sounders MLS team.
Beyond this, he invested hundreds of millions of dollars to research disease, artificial intelligence, and bioscience. He also contributed substantial funding to organizations working to fight the 2013-2016 Ebola epidemic in West Africa. He established the Museum of Pop Culture in Seattle, along with a number of other institutions to showcase his collection of art, aircraft, computers, and memorabilia.