Offer your thoughts or opinion on the input financial query or topic using your financial background.

Why does it matter if a Central Bank has a negative rather than 0% interest rate? 
That is kind of the point, one of the hopes is that it incentivizes banks to stop storing money and start injecting it into the economy themselves. Compared to the European Central Bank investing directly into the economy the way the US central bank has been doing. (The Federal Reserve buying mortgage backed securities) On a country level, individual European countries have tried this before in recent times with no noticeable effect.