In a prepared statement to the Joint House and Senate Economic Committee, Bernanke said the central bank would stick by its accommodating monetary policies, especially while many workers remain underemployed or out of work.
However, MarketWatch reported, Bernanke, in a question-and-answer period after reading his prepared remarks, said a "step down" in the Fed's quantitative easing program -- its asset purchasing program -- could come soon.
"In the next few meetings we could take a step down in our pace of purchase," Bernanke said.
Investors reacted accordingly, erasing early gains.
The Dow Jones industrial average closed off 80.41 points on the day, down 0.52 percent, to 15,307.17. The broader Standard and Poor's 500 lost 13.81 points or 0.83 percent to 1,655.35 and the tech-heavy Nasdaq shed 38.82 points or 1.11 percent to 3,463.30.
On the New York Stock Exchange, 688 issues advanced while 2,431 declined on total volume of 4.3 billion shares traded.
On foreign markets, Japan's Nikkei 225 gained 246.24 points or 1.6 percent to 15,627.26. In Europe, London's FTSE 100 added 36.40 points or 0.53 percent to 6,840.27.
The 10-year treasury note was yielding 2.044 percent.
Crude oil lost $2.04 and settled at $94.14 a barrel. Gold dropped $8.70 to $1,368.90 per troy ounce.
On currency markets, the euro fell to $1.2853 compared to $1.2906 Tuesday. Against the yen, the dollar rose to 103.12 yen from 102.49 Tuesday.
On the Chicago Board of Trade July corn gained 18 cents to $6.58, soybeans gained 13 3/4 cents to $14.92 and wheat gained 6 1/2 cents to $6.87.