Palantir Technologies has created one of the most dramatic stories on Wall Street this year, defying conventional investment narratives. In 2025, it became the top-performing stock in the S&P 500, surging over 106% and at points climbing 144% from the start of the year—outpacing even AI heavyweights like Nvidia.

Palantir shares tumbled Tuesday afternoon, extending recent losses as a high-profile short seller fueled worries the stock could be overvalued after a strong run earlier this year.