The Brexit vote could cause a huge buying opportunity: Wells Fargo

Britain's upcoming referendum on whether to quit the European Union has created considerable market volatility. According to one Wall Street firm, however, investors who panic and sell if the Brexit wins will do so at their own peril.

"If there is an exit vote, you know we want our clients in here stepping in to buy U.S. large-cap stocks," Scott Wren, Wells Fargo Investment Institute's senior global equity strategist, said recently on CNBC's "Futures Now." "After we get finished with the noise and the volatility, after a few weeks of that, you know people will have wished they bought stocks."

Britain will hold a referendum June 23 on whether to leave or remain in the 28-member European Union. British advocates of leaving believe the country is being held back by the political and economic union.

Wells Fargo hasn't issued any official odds on the likelihood of a Brexit. But other firms, such as Morgan Stanley, put the probability just below 50 percent.

"I think that whatever outcome this vote is, it is in no way, shape or form going to change the trajectory of the domestic economy in particular or the international economy over the next 12 to 18 months," he said.

Wren, who is one of Wall Street's biggest bulls, expects the S&P 500 Index to end the year between 2,190 and 2,290. That represents as much as a 9 percent gain from current levels.