The S&P 500 ended a choppy session slightly lower on Wednesday as losses in technology shares weighed down the index even after the U.S. Federal Reserve issued a statement that cemented expectations interest rates would stay near zero for a prolonged period.

The index initially extended gains and the Dow briefly gained more than 1% in afternoon trading after the Fed in its policy statement kept rates near zero and promised to keep them near there until inflation is on track to "moderately exceed" the U.S. central bank's 2% inflation target "for some time."

New economic projections released with the policy statement showed most policymakers see interest rates on hold through at least 2023.

But the market lost ground heading into the close, led by losses in technology shares.

"The Fed is going to be very supportive of the economy and Powell wants Congress to be more stimulative," said Tim Ghriskey, chief investment strategist at Inverness Counsel in New York, New York. It's a worry congress isn't being supportive."

The central bank's two-day meeting is its first under a newly adopted framework that promises to shoot for inflation above 2% to make up for periods where it runs below that target.

Unofficially, the Dow Jones Industrial Average rose 38.17 points, or 0.14%, to 28,033.77, the S&P 500 lost 15.62 points, or 0.46%, to 3,385.58 and the Nasdaq Composite dropped 139.86 points, or 1.25%, to 11,050.47.