We find that the firms included in the S&P 500 index are characterized by large increases in earnings, appreciation in market value, and positive price momentum in the period preceding their index inclusion. This strong preinclusion performance predicts 1) the permanent increase in market value...

We find, unlike earlier studies, that there is no rise in the market betas of stocks that enter the S&P 500 index when the estimated factor model is that of Fama and French (1993). We also find that SMB and HML factor betas decline after the stocks are added to the index. This decline is...