We eximine whether the predictability of future from past is due to the market's underreaction to information, in particular to past earnings news. Past return and past earnings surprise each predict large drifts in future returns after controlling for the other. Market risk, size, and book-to-market effects do not explain the drifts. There is little evidence of subsequent reversals in the returns of stocks with high price and earnings momentum. Security analysts' earnings forecasts also respond siuggishly to past news, especially in the case of stocks with the worst past performance. The results suggest a market that respoonds only gradually to new information.
