U.S. stocks fell, reversing an earlier rally, as the International Monetary Fundsaid risks of turmoil in emerging markets and of deflation in the euro area are threatening the global economy. In a note prepared for central bankers and finance ministers from the Group of 20, the IMF said the recovery is still weak and “significant downside risks remain.”A January global growth forecast of 3.7 percent for this year, from 3 percent in 2013, hinges on recent market volatility from Turkey to Brazil being short lived, the IMF staff wrote.