Banks in Europe could experience more volatility ahead of the June vote on whether Britain should leave the European Union trading block, UBS Chairman Axel Weber warned on Thursday.
"I see some further challenges over the summer," Weber told CNBC's "Worldwide Exchange." "We have a very difficult debate in Europe about Brexit with some downside risk."
Calling it a close call, Weber predicted Britons will vote to stay in the EU.
"It's very hard to prepare for a situation like that," Weber said. "So we're concerned about this short-term volatility, but medium to long term, we have quite a positive view."
Companies need "optionality," and in that sense, he said, UBS is positioned well. The bank's main operations are spread across European cities within the same time zone, but the bank also has a strong presence in London.