St. Louis Federal Reserve President James Bullard's view that a so called Brexit doesn't matter much to the U.S. is "extremely superficial," Citigroup's chief economist, Willem Buiter, said Friday.
Bullard told CNBC's "Squawk Box" on Thursday that he did not think Britain's exit from the European Union represents a "risk event" to the U.S. economy.
U.K. Prime Minister David Cameron has scheduled a referendum on EU membership for June 23.
"It doesn't really matter for the U.S. whether the U.K. is in or out," Bullard said.
"If the U.K. votes yes then nothing has changed. If the U.K. votes no, now you've got three years of negotiation to figure out how the hell to get out of this, or possibly some other kind of free trade agreement that isn't exactly the same as being in the EU," he explained.