By Scott Ronalds

Hard assets can be a good source of diversification in a portfolio, as their prices or market values can have a low degree of correlation to stocks or bonds. Commodities like gold and oil can act as a hedge against inflation (although not always). The same goes for real estate, which can also provide a nice stream of income. And a case can be made for fine wines, art and antique cars. Now, a start-up out of San Francisco wants to add running backs and wide receivers to the list.

As reported in The New York Times last week, Fantex Holdings has announced the opening of a marketplace for investors to buy and sell interests in professional athletes. The company plans to create stocks that are “tied to the value and performance of an athlete’s brand.” First up is Houston Texans running back Arian Foster, who will be the subject of an initial public offering (IPO), which Fantex hopes will raise over $10 million.

Investors curious about investing in a pro athlete in this manner would be wise to carefully consider the risks. Fantex notes in its marketing materials, “The offering is highly speculative and the securities involve a high degree of risk. Investing in a Fantex Inc. tracking stock should only be considered by persons who can afford the loss of their entire investment.”

A key risk of investing in hard assets is their illiquidity and the challenges of dealing in a limited secondary market. While selling a leaky building or a case of poorly-rated Bordeaux can be challenging and stressful, finding a buyer for a quarterback with a torn tricep or a linebacker with a lengthy drug-related suspension could be all but impossible.

Professional athletes are traded all the time in office pools and fantasy leagues. They’re called fantasy for a reason. Best to leave them out of your portfolio.