Fractional Reserve Banking
Fractional reserve banking is the system in which commercial banks hold only a fraction of depositors' funds as reserves and lend out the remainder, enabling banks to create money and multiply the credit available in the economy.
Fractional reserve banking is the foundational operating model of modern commercial banking. Under this system, a bank that receives $100 in deposits does not keep all $100 in a vault. Instead, it retains a fraction — historically set partly by Federal Reserve reserve requirements, now largely by a bank's own risk management and liquidity standards — and lends out the rest. The borrowers spend those funds, which get deposited elsewhere in the banking system, where a fraction is again retained and the rest lent out. Through this multiplier process, the banking system as a whole creates far more credit than the original deposit base would suggest.
The money multiplier concept formalizes this dynamic. If banks collectively hold 10% of deposits as reserves, a $1,000 initial deposit could theoretically support up to $10,000 in total deposits across the system (1,000 / 0.10). In practice, the money multiplier is less mechanical and depends on how much cash people hold outside the banking system, how much excess reserves banks choose to hold, and the demand for loans from creditworthy borrowers.
In March 2020, the Federal Reserve reduced reserve requirements to zero for all depository institutions, eliminating formal reserve requirements for the first time in American history. Banks still maintain reserves for operational liquidity, clearing settlement, and internal risk management purposes, but no regulatory minimum currently mandates a specific ratio. The Fed instead manages monetary conditions through interest on reserve balances (IORB) — the rate it pays banks on reserves held at the Fed — which influences banks' incentives to lend versus hold reserves.
Fractional reserve banking creates both economic benefits and systemic fragility. The credit creation it enables finances homes, businesses, and government operations. But it also means that a bank whose loans sour can face a liquidity crisis if depositors demand their money back simultaneously, a scenario that deposit insurance, the FDIC's resolution authority, and the Fed's lender-of-last-resort function are designed to prevent.
Understanding fractional reserve banking is essential for grasping how the Federal Reserve's monetary policy actions transmit through the economy and how changes in credit conditions affect asset prices and economic activity.