This new S&P 500 stock has been a multibagger and has compelling growth prospects.One of the newest additions to the S&P 500 (^GSPC +0.13%) soared long before joining the index, but this could just be the beginning of a long bull run.Emcor Group (EME 0.68%) joined the S&P 500 index in September. The stock has been an unstoppable multibagger, soaring 200% since the beginning of 2024 and more than quadrupling investors' money in just three years.Several analysts still have a buy rating on Emcor. One of them i ...