Into uncharted territory Earning something for your cash was a way to reward you for parting with it temporarily and compensating you for the risk it might not get paid back. That price has fluctuated, but it was always a positive number. It doesn't have to be: With a glut of global savings that started even before the 2008-09 financial crisis, central bankers slashed interest rates to almost nothing and finally to zero. They also "printed" electronic money to buy trillions of dollars in bonds to push down the longer-term rates that they can't control directly