British lawmakers are set to vote Tuesday on whether to approve Prime Minister Theresa May’s Brexit deal that would take the country out of the European Union.

Whatever the outcome, the world’s fifth-largest economy is set to take a massive hit — and so could the U.S.

Brexit has already proven its potential to upset other economies. “With the original referendum with respect to Brexit … if you look at the Dow, there was a tremendous drop post the vote,” said Tifphani White-King at Mazars USA.

The Dow Jones Industrial Average lost 608 points, or almost 3.4 percent, the day after the vote — and the pain didn’t stop there. Global markets lost $2 trillion in value. The U.S. dollar increased in value, and “that’s not always a good thing,” White-King said. A higher dollar makes U.S. exports more expensive for buyers in other countries. It also means stocks and U.S. investments are more expensive for international buyers.