Agricultural markets rose broadly. Wheat had its biggest rally since April on bargain buying and expectations the grain will be used as a livestock feed.
The rally in farm futures helped the 19-commodity Thomson Reuters-Jefferies CRB index close up 0.5 percent for its biggest gain since June 3, after being subdued the past two weeks on uncertainties over what the Fed might do.
Bernanke told a news conference after a two-day Fed meeting that the central bank expects to slow the pace of its bond purchases later this year and bring them to a halt around mid-2014.
Oil prices closed little changed at the end of Wednesday's official session and fell after-hours as the market digested Bernanke's remarks.
The Fed's stimulus has been responsible for many of the highs in commodity prices since the financial crisis, with the central bank committed to buying $85 billion of bonds a month under its third and latest quantitative easing plan.
Benchmark Brent crude oil out of Europe's North Sea finished up 10 cents a barrel at $106.12. Prices turned lower in post-settlement trading, hitting a low of $105.55.
In New York, the front-month contract for US crude finished down 20 cents at $98.24 per barrel and slipped below $98 after the close.
Aside from the news on the Fed, oil was weakened by data showing US crude stocks rose by 313,000 barrels last week against market forecasts of a 500,000 barrel decline.
The spot price of gold was down 0.5 percent at around $1,360.60 an ounce by 3:10 p.m.
US gold futures for August settled up $7.10 at $1,374 an ounce, with volume at around 113,000 lots versus its 30-day daily average of 212,000, Reuters data showed.
Copper fell to a six-week low, finishing down for a third straight day. Three-month copper on the London Metal Exchange slid 1.1 percent to a session low of $6,925 a tonne, its weakest since May 3.
Grain markets rose across the board, with wheat the biggest mover. Wheat's front-month July contract on the Chicago Board of Trade ended up 19-1/2 cents, or nearly 3 percent, at $7.07 per bushel.