Take Vernon Davis, for example. The tight end for the San Francisco 49ers currently offers roughly 421,100 shares, which have so far traded between $10 and $12.50 a share. Davis agreed to give up 10 percent of his brand-related cash flow to Fantex for investors. In return, he received a $3 million payout.
The deal means Davis must strike a balance between his career as a professional athlete and the realization that he's a walking and talking brand that reports to Fantex.
"If he has a material injury, then obviously he would have to disclose that to us and we would disclose that to the investors because technically, people are investors in Fantex Inc., not technically in Vernon Davis," Buck French, co-founder and CEO of Fantex, said Wednesday on "Squawk on the Street." "His obligation is contractual to us. If he's working on a deal or doing something that's material to his future cash flow stream, then obviously he shouldn't and won't disclose that to other people."
Read MoreWanna buy an NFL team? Buffalo Bills is on the market
Davis, who has twice played in the Pro Bowl, told "Squawk on the Street" he plans to play football as long as he can. The opportunity to build his brand and allow people the opportunity to invest in him was nothing less than a "wise decision."
"It's fun. I like being a security," Davis said. "It's fun. It's a lot of fun. It's exciting."
—By CNBC's Drew Sandholm.