A new marketplace called Fantex will enable investors to purchase stock in professional athletes. And this isn’t a fantasy league. You are essentially buying a piece of a real person. The first IPO is Houston Texans’ running back Arian Foster. “Buying shares in the deal will give investors an interest in a stock linked to Mr. Foster’s future economic success, which includes the value of his playing contracts, endorsements and appearance fees.” Those who find that investing in Internet startups isn’t risky enough can now invest in something even riskier: NFL running backs (most of whom have a career span that strongly resembles that of Kozmo).