Large price changes on small scales

In this study we examine the evolution of price, volume, and the bid–ask spread after extreme intraday price changes on the NYSE and the NASDAQ. We find that due to strong behavioral trading there is an overreaction. Furthermore, we find that volatility which increases sharply at the event decays according to a power law with an exponent of ≈0.4, i.e., much faster than the autocorrelation function of volatility.