How naive is the stock market's use of earnings information?

Rendleman, Jones, and Latane (1987) and Bernard and Thomas (1990) hypothesize and report evidence that investors use a 'naive' seasonal random walk model, at least in part, for quarterly earnings. We show that the market acts as if it: (1) does not use a simple seasonal random walk model; (2) does exploit serial correlation at lags 1-4 in seasonally-differenced quarterly earnings; (3) does use the correct signs in exploiting serial correlation at each lag; but (4) underestimates the magnitude of serial correlation by approximately 50% on average. We discuss the consistency of alternative hypotheses with our evidence.