Appaloosa's billionaire boss reversed course in the second quarter by becoming a big-time buyer of Nvidia stock and a seller of the hottest AI-networking company.

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%.

Nvidia ( NVDA 0.94%) owns stock in publicly traded companies as part of its treasury strategy. Its $4.3 billion portfolio included six positions as of the June-ending quarter, but two accounted for 95% of invested assets: 91% was allocated to CoreWeave ( CRWV -3.17%) and 4% was to Arm Holdings ( ARM 1.52%).

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

Beyond the Nvidia Hype Over the past few years, Nvidia (NASDAQ:NVDA) has been a stellar investment, riding the wave of artificial intelligence (AI) and semiconductor demand. Its stock has soared, delivering remarkable returns for investors who bet on its innovative chips powering AI data centers and gaming.

While most of AI's power players have already reported, the ultimate industry bellwether, Nvidia ( NVDA 0.94%), has yet to step up to the plate. The semiconductor giant is scheduled to announce results on Aug. 27, and expectations could not be higher.

NEW YORK — Wall Street faded Aug. 19 following drops for Nvidia and other stars that have been riding the mania surrounding artificial-intelligence technology.