U.S. stocks ended lower Wednesday, reversing gains after comments by Federal Reserve Chair Jerome Powell left investors wondering what the U.S. central bank's next move would be with interest rate hikes.

Indexes initially held onto gains following the Fed's statement. It increased interest rates by a quarter of a percentage point, as expected, and signaled it could pause further hikes.

The unanimous decision lifted the U.S. central bank's benchmark overnight interest rate to the 5.00%-5.25% range, the 10th consecutive increase since March 2022.

At the press conference following the statement, Powell said the Fed still views inflation as too high, and said it was too soon to say the rate hike cycle is over.

"The Fed continues to walk the tightrope, and that is they're trying to strike a balance between their inflation fighting credibility while trying to engineer a soft landing," said Michael Arone, chief investment strategist at State Street Global Advisors in Boston.

Heading into the session, investors had been anxious for any signals from the U.S. central bank on whether Wednesday's increase would be the last hike for now.

According to preliminary data, the S&P 500 lost 27.65 points, or 0.67%, to end at 4,091.93 points, while the Nasdaq Composite lost 50.62 points, or 0.46%, to 12,025.33. The Dow Jones Industrial Average fell 261.10 points, or 0.78%, to 33,423.43.

"Anybody that was hoping for an inclination toward that scenario, it doesn't sound like they're getting that," said Alan Lancz, president of Alan B. Lancz & Associates Inc., an investment advisory firm based in Toledo, Ohio. "It's inconclusive."

Investors worry that higher rates will eventually tip the economy into recession.

Earlier, data showed U.S. private employers boosted hiring in April, but showed signs the labor market was slowing following several rate hikes.

A separate report showed U.S. services sector maintained a steady pace of growth in April, but higher input prices indicated inflation could remain elevated for some time.

Advanced Micro Devices shares fell after the chipmaker forecast quarterly sales below estimates due to a weak PC market.