Since the European Central Bank and the Bank of Japan moved their interest rates negative, a debate has swirled over the practical and theoretical impacts of the move.

But according to the CEO of a major US bank, if the US Federal Reserve were to do the same, it would have a serious practical impact on customers' bank accounts.

Analysts at Deutsche Bank hosted meetings with PNC Bank's chairman and CEO, Bill Demchak,last week and addressed the possibility of negative rates.

The answer was simple: "If rates go negative, consumer deposit rates go to zero and PNC would charge fees on accounts."