The Fed will boost its balance sheet by half a trillion dollars over the next half year, economists say. In a new survey crafted to gauge sentiment on the Fed's QE policies, 70% of the respondents believed the Fed will restart QE; of those 80% think it will happen before year-end. "The trigger for the resumption of quantitative easing late this year will be an increase in unemployment back into double-digits," Moody's Mark Zandi said.