Anticipating volatile and illiquid markets conditions round the Nov. 8 election, Saxo said the margin requirements on most major currency pairs would be increased to 2 to 3 percent, while higher deposits would also be required for some single equity, index and fixed income products.

Saxo said it was also increasing its margin requirements on the Russian rouble to 10 percent.

"We want to ensure that our clients take advantage of trading opportunities with responsible leverage," said Claus Nielsen, Saxo's head of markets.

"Although the U.S. election outcome might not create as much volatility as was created by the surprise outcome of the UK's EU Referendum, there is no doubt that a surprise outcome of the election can create strong volatility," he added.

(Reporting by Jemima Kelly; Editing by Patrick Graham)