Banks love their "golden deposits" - highly profitable (for them) non-interest-bearing accounts. These deposits are sticky, representing 25-32% of bank deposits, including personal checking accounts and Corporate treasury accounts.  Another place cash can be earning nothing is in Broker dealer and mutual fund sweep accounts.  This is where money transferred into brokerage accounts lands and sits until invested. Proceeds of the sales of securities and income generated from securities (if not automatically reinvested) also land in the sweep accounts.  A little attention to putting this money to work and minimizing how much and how long cash sits idle can result in significant additional income.