For banking, negative interest rates are a bit like a stroll into the peculiar world of quantum mechanics, where subatomic particles often behave in strange and unexpected ways.
Across Europe, negative interest rates have prompted banks to engage in some curious practices. In Germany, banks have hoarded physical cash in vaults because it was cheaper than holding large balances at the central bank, some Irish credit unions have returned money to savers when above a certain threshold, and several banks in Denmark charge negative interest rates on some mortgages — i.e. pay the borrower interest.
