Online sports entertainment company OneSeason.com has closed a $3.5 million first round of funding; Charles River Ventures led the investment. The SF-based company will use the funds to add social features and a marketplace around its virtual sports exchange, which lets members use real money to invest in virtual “shares” of their favorite athletes. In a fantasy sports twist, the athletes’ values fluctuate based on their real world performance. OneSeason.com was founded in 2007, and competes with CitizenSports subsidiary ProTrade. VentureBeat notes that private investor Phil Drayer backed the company’s $250,000 seed round. Release.