Mark Wahlberg and Eminem are just two of the biggest names investing in this fast-rising sneaker stock market startup. StockX, which is a marketplace where sneakerheads can resell, well, sneakers, has raised $6 million in a new fundraising round. It's list of investors include rapper Wale, Cleveland Browns cornerback Joe Haden and TV host/radio personality DJ Skee. Co-founder and CEO Josh Luber claims the resell market for sneakers is worth $6 billion globally. The money raised will allow StockX to expand into other categories, like watches and handbags.