Stephen Guilfoyle, a 30-year Wall Street veteran who now runs Sarge986 LLC, a family trading operation, attributed Palantir’s recent decline to profit-taking by short-term traders. He noted that the “swing crowd” likely locked in gains as the stock tested a key moving average, accelerating the sell-off.

Nvidia, Palantir and other superstar stocks that had surged in the mania surrounding artificial-intelligence technology are dragging Wall Street lower again on Wednesday.The S&P 500 fell 0.5% and was heading for a fourth straight loss after setting an all-time high last week.