Crude dropped as much as 1.5% today, the most in two weeks, after President Barack Obama said al-Qaeda leader Osama bin Laden had been killed, boosting expectations that risks of supply disruptions in the Middle East will ease. Silver had its biggest intraday drop since October 2008 after CME Group Inc. increased futures margins. Cotton futures plunged 21% in April, also the most since October 2008.

"The key reason commodities outperformed stocks and bonds is the weak dollar," said Evan Smith in San Antonio, who helps manage $1 billion at U.S. Global Investors Inc. "Commodities will continue to outperform stocks and bonds. Over the next three to six months, we don't see a backstop for the dollar."

The Dollar Index had its worst month since September and the currency weakened against all 16 of its major peers, according to data compiled by Bloomberg. The New Zealand dollar appreciated 6.3%, the euro 4.6% and the Japanese yen 2.3%, the data show.

'Dovish' Bernanke

Bernanke said April 27 that the end of the Fed's $600 billion bond-buying program in June probably won't have a "significant" effect on financial markets or the economy, and the central bank will likely continue reinvesting proceeds from maturing debt after June.

"He's remarkably dovish, dismissing inflation," said Anthony Valeri, a San Diego-based market strategist at LPL Financial Corp., which manages $293 billion. "It does keep pressure on the dollar."

The Fed's program to bolster the economy, which has been in place since the 2008 financial crisis, contrasts with China, which raised borrowing costs four times since October and increased reserve requirements 10 times since the start of 2010 to tame the fastest inflation since 2008.

Bonds worldwide returned the most since August, according to Bank of America Merrill Lynch indexes. Within that market, corporate bonds handed investors 1.3% and government debt returned 0.8%, the gauges show.

Goldman, Dow Chemical

The MSCI All-Country World Index reached 356.9 points on April 29, extending this year's gain to 7.9%. The S&P 500 Index advanced 2.9% in April, the Stoxx Europe 600 Index 2.9% and the MSCI Asia Pacific Index 2.7%. Stocks worldwide added $2 trillion of market capitalization in the month, the most since December, data compiled by Bloomberg show.