The median of forecasts from economists at 15 U.S. primary dealers - the large financial institutions that deal directly with the Fed - was for the central bank to buy $1.25 trillion of assets, which was up from a median of $1 trillion in a similar poll conducted by Reuters on March 8.

The forecasts for the size of Fed purchases in the latest round of stimulus mostly ranged from $885 billion to $1.6 trillion.