Explainer: How does negative interest rates policy work?

LONDON (Reuters) - The European Central Bank doubled down on its negative rate policy on Thursday, meaning banks will now have to pay 0.5% interest simply for depositing much of their spare cash with it - an attempt to make them lend more to kickstart the economy.While such a policy is widely considered valid only for economies in Europe and Japan with chronically low inflation and weak growth, the idea is attracting other supporters elsewhere - not least U.S. President Donald Trump, who has..