Interest rates are now negative, below zero, for a growing number of borrowers, mainly in the financial markets. It means in effect they are being paid to borrow someone else's money. So what on earth is going on?
Perhaps the first thing worth stating is that negative interest rates are probably not coming to a High Street near you in the near future.
It is a phenomenon that has had economists scratching their heads. In fact there is a well-known (to economists) term for the idea that interest rates shouldn't go below zero. It's the "zero lower bound".
It has been breached. There is probably a limit to how much further we can go in that direction. But at the very least recent developments show the zero lower bound is not as rigid as it was widely thought to be.
One point worth spelling out is that we are not talking about negative real interest rates. That is where you have an interest rate that may be above zero but it is lower than inflation. That means that a borrower's total repayments have less purchasing power than the amount they first borrowed.
That is not so unusual. As long as there is at least moderate inflation, central banks can get real rates below zero to stimulate economic recovery and there have been many episodes of that.
No. We are talking here about what economists call nominal interest rates below zero, making no allowance for rising (or falling) prices.
The reason it is so strange is this: normally a potential lender can choose not to lend and just sit on the funds. That is equivalent to getting a nominal interest rate of zero. Not great, but surely better than an interest rate of less than zero. That is the basic idea behind the concept of the zero lower bound.