U.S. stocks experience significantly better returns during years when an American model graces the cover of the Sports Illustrated swimsuit issue than during years when the magazine cover features a foreign model, history shows. The S&P 500 had an average return of 14.3 percent during the 17 years since 1978 that featured an American, with positive returns a whopping 88 percent of the time, according to the Bespoke Investment Group blog. That’s about four percentage points above the average return during the years that featured a model from another country. The difference would be even greater, if not for the failure of the indicator in 2008, when the S&P 500 plunged 37 percent after Sports Illustrated featured American-born Marisa Miller and Lehman Brothers collapsed. Last year, Russia’s Irina Shayk graced the cover and the U.S. benchmark subsequently returned a disappointing 2.1 percent. [CNBC]