The week’s biggest news for Wall Street is likely arriving on Friday, when Federal Reserve Chair Jerome Powell will give a highly anticipated speech in Jackson Hole, Wyoming. The setting has been home to big policy announcements from the Fed in the past, and the hope on Wall Street is that Powell will hint that an interest rate cut is coming soon.

Dow futures slipped slightly on Wednesday as investors adopted a cautious stance ahead of Federal Reserve Chair Jerome Powell’s upcoming remarks at the Jackson Hole Symposium.

Wall Street shares dropped on Wednesday, with a tech selloff extending into a second day, while a key meeting of central bankers later this week remained in focus for currency and rates traders.

Nvidia, Palantir and other superstar AI stocks are dragging Wall Street lower again. The S&P 500 fell 0.5% Wednesday and was on track for a fourth straight loss after setting an all-time high last week.

The tech sector was behind much of the market recovery from the April selloff, but investors have started to take stock of the elevated valuations, sending the S&P 500 and the Nasdaq to their worst day in more than two weeks on Tuesday.

The heaviest weight on the market was Nvidia, whose chips are powering much of the move into AI. It sank 3.5%.

U.S. stock indexes ended mixed Aug. 20 after Nvidia, Palantir and other superstar stocks pared most of their steep morning losses.

The S&P 500 slipped 0.4% and is on track for a third straight modest loss after setting its all-time high last week. The Dow Jones Industrial Average was up 8 points, or less than 0.1%, as of 11:50 a.m. Eastern time, and the Nasdaq composite was down 1%.

Wall Street faded on Tuesday following drops for Nvidia and other stars that have been riding the mania surrounding artificial-intelligence technology.