Palantir Technologies (PLTR -1.91%) was the best performing stock in the S&P 500 (^GSPC 0.63%) in 2024. The company saw its share price surge 340% as robust demand for its artificial intelligence platform led to impressive financial results throughout the year.Palantir has maintained its momentum in 2025. Its year-to-date return of 57% means it is once again the best performer in the S&P 500, partly because investors have shown a clear preference for software and services companies that may escape tariffs u ...