M3 is the total money supply, which includes M2 money as well as large time deposits, institutional money market funds, short-term repurchase agreements and larger liquid funds.
M3 is closely associated with larger financial institutions and corporations than with small businesses and individuals.
M3 has traditionally been used by economists to estimate the total money supply in an economy and by governments to guide policy and control inflation in the medium to long term.
As a measure of money supply, M3 has largely been replaced by zero-maturity money (MZM).
M3 is still published as a source of economic data, but mainly for ease of comparison with historical data.