Palantir Technologies Inc. ($PLTR) has emerged as the leading stock in the S&P 500 for the year-to-date, experiencing a remarkable surge of 275%. This performance surpasses that of Vistra Corp. ($VST), which has gained 268%, and Nvidia Corp. ($NVDA), which is up 187%. Palantir's recent entry into the S&P 500 has positioned it as a key player in the market, drawing attention from investors and analysts alike.