Switzerland's surprise move weakens yuan

US currency demand increases after euro cap abandoned

China's yuan fell the most in four weeks as the Swiss National Bank's surprise move to abandon a cap to the euro boosted demand for the greenback.

The Swiss franc jumped as much as 41 percent on Thursday in London after the central bank scrapped a three-year-old policy of preventing the currency from strengthening beyond the 1.20 level against the European single currency.