Excess Reserves of America's Commercial Banks: April 2011
April 25, 2011
This is a FRED chart published by the Federal Reserve Bank of St. Louis.
Increases in excess reserves offset increases in the Federal Reserve System's monetary base (balance sheet).
This is why prices did not double in response to the FED's doubling of the monetary base in 2008-9.
The increase has matched the increase in the FED's purchases of bonds in 2011.