One of the factors that caused the gap to occur at the beginning of the week could be because there was a fairly large incident at the weekend after the market close on Friday, so the market compact took action in one direction when the market opened on Monday. However, it could also be because market participants acted impulsively and caused prices to rise too high or fall too low on Friday. Market participants only realized they were overreacting after a weekend recount, so decided to ?normalize? their trading positions on Monday. As a result, prices that initially increase can lead to a Down Gap; or the price that originally decreased even rose (Up Gap).