Source: Board of Governors of the Federal Reserve System (US)  

Release: H.6 Historical Data  

Units:  Billions of Dollars, Seasonally Adjusted

Frequency:  Weekly, Ending Monday

For details, please see http://www.federalreserve.gov/releases/h6/hist/.
On March 23, 2006, the Board of Governors of the Federal Reserve System ceased publication of the M3 monetary aggregate and its components. For more information, please, refer to http://www.federalreserve.gov/releases/h6/discm3.htm.