In times of negative interest rates depositors are essentially being charged to store their money in the bank.
http://myinvestingnotes.blogspot.com/2020/12/negative-interest-rates.html
Negative interest rates has been the case in the past, in countries including Switzerland and Denmark.
This encourages consumers and businesses to put their money in the economy at large by buying additional goods and services.
http://myinvestingnotes.blogspot.com/2020/12/negative-interest-rates.html