Palantir Technologies shares fell as much as 9 % on Tuesday, extending a five-session slide that has erased about 16 % of the software maker’s market value since 13 August and marked its steepest five-day drop since March. The stock closed near $158, down from a record high of roughly $190 reached last week, trimming the company’s capitalisation to about $430 billion. The retreat came amid a broader sell-off in high-growth artificial-intelligence names, with the Nasdaq Composite down about 1.5 % in afternoon trading. Nvidia, Advanced Micro Devices and Meta Platforms also traded lower, underscoring investors’ rotation out of some of 2025’s top performers. Pressure on Palantir intensified after short-seller Citron Research issued a bearish note on Monday that called a $40 share price “generous,” arguing the company’s valuation is inflated relative to OpenAI’s recent $500 billion implied valuation. Options markets showed an elevated put bias, suggesting traders are hedging against further downside. Even after the pullback, Palantir remains the S&P 500’s best-performing stock this year, buoyed by enthusiasm for its artificial-intelligence platform, its first-ever $1 billion revenue quarter and a string of U.S. government and commercial contracts. The shares still trade at roughly 93 times forward sales, far above the multiples of larger technology peers.