The Dollar Index fell to a more than three-month low after Federal Reserve Chairman Ben S. Bernanke said he wouldn’t rule out further bond purchases to boost growth and reduce unemployment, which he called a “grave concern.”

The currency fell against all but one of its 16 most-traded peers after Bernanke told central bankers and economists at an annual forum in Jackson Hole, Wyoming, that “nontraditional policies” shouldn’t be ruled out if economic conditions warrant. The dollar also weakened as reports showed business activity in the U.S. expanded more slowly this month and demand for U.S. capital goods dropped in July.

The pound is set for a monthly gain versus the greenback as a report showed U.K. house prices rose in August, easing concern that the recession is worsening.