Sept. 8 (UPI) -- Tennis legend Serena Williams invested in women's 3-on-3 basketball league Unrivaled, bringing the its value up to $340 million, the league announced Monday. Williams' venture capital firm, Serena Ventures, along with fellow tennis icon Billie Jean King and soccer star Alex Morgan 's Trybe Ventures, participated in the Series B investment round led by Bessemer Venture Partners and Warner Bros. Discovery. A person familiar with the league told CNBC the league's valuation rose by