Description Available in: The Professional Fighters League (PFL) is an American mixed martial arts league founded by venture capitalist Donn Davis in 2017 and launched in 2018, following the acquisition and restructuring of the former World Series of Fighting (WSOF) promotion in 2017 by MMAX Investment Partners. It is the first major MMA organization in which individual athletes compete in a regular season, post-season and championship, rather than on a year-round basis.