The SPDR S&P 500 ETF is down more than 0.3 percent in after hours trading. The Invesco QQQ is down almost 0.5 percent.

"It's falling on the headline that for Michael Cohen, one of the counts was for making a payment to Stormy Daniels, at the direction of an unnamed candidate," Said Peter Boockvar, the chief investment strategist at Bleakley Financial. "Michael Cohen's legal problem is now a legal problem for Trump."

The S&P 500 futures fell 7 points, and Dow Jones futures were down 69 points as trading began at 6 p.m. ET

S&P 500 futures fell in evening trading, pointing to a possible lower opening for stocks on Wednesday. The move came after President Donald Trump's former lawyer, Michael Cohen, pleading guilty on Tuesday, said a candidate for federal office directed him to pay off a porn star "for the principal purpose of influencing" the election.

Cohen, Trump's former personal lawyer and so-called "fixer," agreed to plead guilty on Tuesday to eight charges related to tax fraud, excessive campaign contributions, making false statements to a financial institution and unlawful corporate contributions.

Cohen admitted to making payments to two women at the direction of an unidentified candidate for political office "to influence the outcome of the election" by keeping information from becoming public. One of the payments, of $130,000, is thought to be a reference to the payment Cohen orchestrated to porn star Stormy Daniels, whose real name is Stephanie Clifford, who is suing Trump.

"This is all noise for the economy and this could be nothing for Trump. That's why the futures came in, the uncertainty of where this whole thing goes," said Boockvar.

News of Cohen's guilty plea was breaking almost at the same time Tuesday afternoon as a jury returned 8 guilty verdicts against Trump's former campaign chairman Paul Manafort. Five of the counts concerned tax fraud, two bank fraud and one failing to file foreign bank account reports. The judge declared a mistrial on 10 other counts.

For now, some strategists said, the Cohen revelations and Manafort case may not be a big deal for the market. The focus may shift to the Fed. The stock market closed Tuesday tied for the longest bull market, and it could break that streak on Wednesday.

"Do you sell stocks on presidential turmoil or do you buy them on the idea the president will be preoccupied with this kind of scandal rather than the trade issues," said Marc Chandler, head of fixed income strategy at Brown Brothers Harriman. "Does the market rally on the fact he's preoccupied?"

"It's uncertainty but stocks closed pretty firm and we just made record highs," Chandler said. If stocks sell off on profit taking on Wednesday "is it really a big deal?"