The Dow Jones Industrial Average and fell for a second day in a row on Wednesday as investors grappled with key testimonies on U.S.-China trade relations, Federal Reserve monetary policy as well as a host of geopolitical issues.

The 30-stock Dow dipped 72.82 points to 25,985.16 as UnitedHealth underperformed. The S&P 500 slipped less than 0.1 percent to 2,792.38, led lower by the communications services and health care sectors. The Nasdaq Composite eked out a small gain, closing nearly 0.1 percent higher at 7,554.51.

The S&P 500 tech sector closed 0.1 percent lower, snapping a 12-day winning streak. Facebook and Alphabet both closed down. The VanEck Vectors Semiconductor ETF (SMH) fell 1 percent. Micron was one of the biggest laggard in the SMH, sliding more than 3 percent.

Stocks fell to their lows of the session as U.S. Trade Representative Robert Lighthizer hinted that a trade deal was not yet certain, saying that any agreement would need to be more than just purchases by China. The deal would need to be specific and include a matter of enforcement, he said. Lighthizer also noted that it would be a "long process" to implement any deal agreed upon in March.

Lighthizer was testifying in front of the House Ways and Means committee. Trade tensions between the U.S. and China lowered this week after President Donald Trump pushed back a deadline on adding additional tariffs on Chinese goods.

"I think market got a bit ahead of itself in term of optimism" around trade, said Shawn Cruz, manager of trader strategy at TD Ameritrade. "You saw the VIX go below 14 and the market really rallied; the S&P 500 got over 2,800."

"The market is now coming back down to reality," Cruz said.