Newt Gingrich has won the South Carolina primary, elevating him to a 25 percent chance to win the Republican nomination in online futures markets. This is the first serious assault we’ve seen on Romney’s once iron grip on this particular set of markets in months, which have barely wavered until tonight in their conviction that he will eventually win the nomination. Still, he continues to be the heavy frontrunner with about a 2 in 3 (66 percent) likelihood of gaining the nomination.