A slowly mean-reverting component of stock prices tends to induce negative autocorrelation in returns. The autocorrelation is weak for the daily and weekly holding periods common in market efficiency tests but stronger for long-horizon returns. In tests for the 1926-85 period, large negative autocorrelations for return horizons beyond a year suggest that predictable price variation due to mean reversion accounts for large fractions of 3 to 5-year return variances. Predictable variation is estimated to be about 40 percent of 3 to 5-year return variances for portfolios of small firms. The percentage falls to around 25 percent for portfolios of large firms.

A slowly mean-reverting component of stock prices tends to induce negative autocorrelation in returns. The autocorrelation is weak for the daily and weekly holding periods common in market efficiency tests but stronger for long-horizon returns. In tests for the 1926-85 period, large negative autocorrelations for return horizons beyond a year suggest that predictable price variation due to mean reversion accounts for large fractions of 3-5-year return variances. Predictable variation is estimated to be about 40 percent of 3-5-year return variances for portfolios of small firms. The percentage falls to around 25 percent for portfolios of large firms.

This paper examines the effects of unexpected inflation on the returns to the common stock of companies with different short-term monetary positions, and different long-term monetary positions, and different amounts of nominal tax shields. Unlike most previous studies of the effects of nominal contracting, we distinguish between expected and unexpected inflation in our tests. Surprisingly, over the 1947-79 period there is little evidence that stockholders of net debtor firms benefit from unexpected inflation relative to the stockholders of net creditor firms. We conclude that wealth effects caused by unexpected inflation are not an important factor in explaining the behavior of stock prices.

This paper examines the effects of unexpected inflation on the returns to the common stock of companies with different short-term monetary positions, and different long-term monetary positions, and different amounts of nominal tax shields. Unlike most previous studies of the effects of nominal contracting, we distinguish between expected and unexpected inflation in our tests. Surprisingly, over the 1947-79 period there is little evidence that stockholders of net debtor firms benefit from unexpected inflation relative to the stockholders of net creditor firms. We conclude that wealth effects caused by unexpected inflation are not an important factor in explaining the behavior of stock prices.