The dollar rose against the Korean won and the Taiwan dollar. Both Taiwan and Korea are major exporters that could be hit by any policies that restrict global trade, such as the tariffs promised by Mr. Trump.

Stephen Innes, a senior trader at Oanda Asia Pacific, said that his retail clients in general are placing smaller currency bets than normal, especially in the yen, and holding those positions for short periods of time. “There’s a lot of in and out, quick trades,” he says. “They’re not holding the positions for longer than 10 to 15 minutes.”

Mr. Innes said that his office in Singapore was noisy at times on Wednesday morning in Asia, with chatter coming through a speakerphone that connected trading desks in Singapore, New York and Toronto. “The squawk box went crazy” as polls closed in Florida, he added.

“If Trump wins…there wi

Close up of the flags of the North American Free Trade Agreement NAFTA members on textile texture. NAFTA is the world's largest trade bloc and the member countries are Canada, United States and Mexico.