Stock returns following large 1-month declines and jumps: Evidence of overoptimism in the German market

We analyze the short-run and long-run performance of the largest 100 German firms that experience monthly stock price changes of more than ±20% between 1990 and 2003. The results indicate that the return patterns following large price increases are consistent with the overreaction hypothesis, but those following price declines indicate underreaction. Thus, our results support an overoptimism hypothesis for the German market. Further, for price decreases we find strong evidence of a size effect, while for price increases, market-to-book-ratios seem to play a role in determining the magnitude of the reaction. No evidence is found supporting the uncertain information hypothesis.