Bankers have done the equivalent of stuffing the mattress in the last few months, despite being prodded by the government to lend the hundreds of billions in cash being pumped into the banking system by the Federal Reserve and other regulators.

They’ve been hoarding cash at the Federal Reserve, some $793 billion of excess reserves as of the end of January, which is more than double the amount of money doled out or pledged to financial companies through the Treasury Department’s $700 billion Troubled Asset Relief Program.

Banks have to stash away a minimal level of reserves, but they can keep extra reserves. Last year at this time, excess reserves totaled $1.7 billion, according to Fed data. Back then, excess reserves were considered uneconomical, since banks could make more profits off lending the money to fellow banks overnight or to clients. But that all changed in October, when the Fed started paying interest.