The Dollar Index fell by the most since the first quarter of2011 after the European Central Bank pledged to protect the eurofrom unraveling and the Federal Reserve committed to reduceunemployment via open-ended debt buying, which may debase the U.S.currency.

Since July 26, when ECB President Mario Draghi said he would do“whatever it takes” to save the euro, the 17-nation currency roseversus 15 of its 16 most-traded counterparts tracked by Bloomberg.Amid the Fed's expansion of monetary stimulus, the Dollar Indexlost 2.1 percent in the third quarter. The Bank of Japan, whichfollowed the Fed and the ECB in expanding its balance sheet by 10trillion yen ($130 billion), is scheduled to announce its nextpolicy decision on Oct. 5.

“The ECB announcement to buy one- to three-year bonds in theperiphery” shaped currency markets last quarter, George Davis,chief technical analyst for fixed income and currency strategy inToronto at Royal Bank of Canada, said in an interview. “It was theopening of a new chapter.”