Everyone uses commodities such as wheat, cocoa, crude oil, butter, coal and electricity. But most investors know that speculating on commodities in the futures markets is only for the pros, and no sensible amateur would bet his retirement or college funds on sugar, silver, orange juice or feeder cattle. One of the most infamous commodities investments, pork belly futures, is shorthand for “how to lose your nest egg in the wink of an eye.” But are commodities really that risky? A shortage of data has left that question unanswered. Until now. Using the most comprehensive data on commodities futures returns ever assembled, Wharton finance professor Gary Gorton and K. Geert Rouwenhorst, finance professor at the Yale School of Management, have reached a surprising conclusion: Commodities offer the same returns as investors are accustomed to receiving with stocks, which are typically viewed as safe enough for ordinary investors.…