Stock market dynamics: Before and after stock market crashes

► We model the dynamics of stock market index returns prior and after major crashes. ► Aftershocks and foreshocks are well defined by the Gutenberg-Richter law. ► Magnitude exhibits scale invariability, self similarity and obeys a power law. ► Also, aftershock sequence obeys the Omori law and power relaxation. ► The relaxation exponent increases with threshold.