Facebook Inc. initially led peers higher in early trading after unveiling new privacy settings in response to criticism about its handling of millions of users’ personal data. But the sector soon took a downturn after Axios reported that President Donald Trump is said to be looking at whether to go after Amazon.com Inc. with antitrust or competition law. Amazon fell as much as 6.2 percent, its worst day in more than six weeks. Other megacap peers including Apple Inc. and Alphabet Inc. also saw their early gains vanish.

“For the first time in a while, traders have no idea what’s going on,” said Michael Antonelli, an institutional equity sales trader and managing director at Robert W. Baird & Co., in a phone interview. “What usually happens is a panic selloff one day precedes a pick-up in futures the next morning. That was the case earlier today, but the dip buyers are gone.”

Facebook rose 1.2 percent at 9:55 a.m. in New York, the second-best performer in the 10-member NYSE FANG+ Index after Twitter Inc. The index had its worst drop in more than three years Tuesday and looks to extend those losses.

“The story around Facebook hasn’t played out yet,” said Michael O’Rourke, JonesTrading’s chief market strategist, by phone. “It’s going to be a long day.”