Stocks gave up an afternoon gain and ended slightly lower on Wall Street on Wednesday. Energy companies helped pull the market lower after crude oil prices sank. The S&P 500 fell 0.1%, the Dow Jones Industrial Average fell 0.2% and the Nasdaq lost 0.1%. The price of U.S. crude oil fell 4%.

Investors closely watched testimony to Congress from Federal Reserve Chair Jerome Powell. He reaffirmed the central bank's determination to raise interest rates and slow inflation. Bond yields mostly fell. The yield on the 10-year Treasury note, which helps set mortgage rates, fell to 3.16%.

During Powell's testimony, the Federal Reserve chair sought to reassure the public that the Fed will raise interest rates high and fast enough to quell inflation, without tightening credit so much as to throttle the economy and cause a recession. Testifying to the Senate Banking Committee, Powell faced skeptical questions about the Fed’s ability to tame inflation, which has surged to the top of Americans’ concerns as congressional elections near.

Democrats wondered whether the Fed’s accelerated rate hikes will succeed in curbing inflation or might instead just tip the economy into a downturn. Several Republicans charged that the Powell Fed had moved too slowly to begin raising rates and now must speed up its hikes.