UBS is deliberating whether to pass on to more of its clients charges on Swiss franc deposits imposed by Switzerland's central banks, CEO Sergio Ermotti said at an investor conference in London.

The third quarter closes on Friday and though banks don't report results for several more weeks, one thing is certain: uncertain economic prospects, volatile financial markets, geopolitical risks and client passivity are still big factors eating into bank profits.

In addition, banks remain hamstrung with negative interest rates in Switzerland and in the eurozone, among others. 

“We may need to start to think about how to pass more negative rates to a broader client base than being able to reprice the asset side of the equation,” UBS CEO Sergio Ermotti said at a brokerage conference.

Until now, the Swiss bank has only charged its wealthiest private banking clients and larger institutional ones for holding Swiss francs. Clients have parked roughly 400 billion in cash piles with UBS.