The Chinese yuan fell to its weakest level against the U.S. dollar since late 2010, after China’s central bank cut its daily-fix value for the currency by the biggest margin since a one-time devaluation in August 2015.

The sharp move in the yuan fixing was a reaction to volatility in currency markets following the U.K.’s Thursday decision to leave the European Union, and especially to a surge in the U.S. dollar Friday as haven currencies jumped.

The People’s Bank of China on Monday fixed the yuan at 6.6375 per U.S. dollar, 0.9% weaker than Friday’s fixing of 6.5776. That move in the fixing level was slightly less than the 1.1% devaluation last August. The currency is allowed to trade up or down 2% from the daily fix.

The yuan weakened further from the fixing level Monday in China’s domestic market, ending at 6.6393 per U.S. dollar after hitting its weakest level since Dec. 24, 2010. That was 0.4% weaker than its Friday closing value of 6.6140 per dollar.

The main reason for the sharply weaker PBOC fix was the 2.5% rally in the U.S. Dollar Index on Friday following the U.K.’s “Brexit” referendum. The British pound plunged 8.1% against the U.S. dollar on Friday, but its effect on the yuan is relatively limited because it makes up just 3.86% of the basket of currencies used by the China Foreign Exchange Trade System to track the yuan’s trade-weighted value. By contrast, the U.S. dollar accounts for more than a quarter of the weighting in the basket. Because of the dollar’s jump, the PBOC set the yuan fixing weaker to reflect market forces.