New York University Professor Nouriel Roubini said curbs placed on U.S. futures trading today shows his prediction that markets will be shut down amid panic selling is coming true.

``This morning, even before the markets in the U.S. opened, the S&P futures fell by more than their daily limit,'' resulting in curbs on futures trading, Roubini told a conference in Madrid today. ``What I said yesterday has already started.''

Roubini said yesterday that policy makers may need to shut down financial markets for a week or two as investors dump assets. Trading in futures on the Standard & Poor's 500 Index and the Dow Jones Industrial Average was limited today after declines of more than 6 percent. Trading of U.S. stocks would be suspended for an hour should the Dow Jones Industrial Average decline 1,100 points to 7,591.25.

``Things are getting worse, they are not getting better,'' Roubini said. There's an increased risk of a ``multi-year economic stagnation'' in the U.S. and ``we have a whole set of emerging market economies in trouble. Even a few of them going bust may cause systemic trouble.''

Russia's RTS exchange today stopped trading after stocks slumped more than 10 percent. Europe's Dow Jones Stoxx 600 Index slid 8.5 percent. The MSCI World index of global stocks has lost 45 percent this year as the fallout from the U.S. housing crisis toppled banks from Seattle to Paris.