sentences:  The number of different stocks that move up or down together were shown to be an indicator of the mimicry within the market, how much investors look to one another for cues.When the mimicry is high, many stocks follow each other's movements - a prime reason for panic to take hold.It was shown that a dramatic increase in market mimicry occurred during the entire year before each market crash of the past 25 years, including the financial crisis of 2007–08.