M and W formation patters.
The first leg rise/fall induces traders to take long/short positions, often after a breakout of a previous area of consolidation.
The center leg reversal trigggers those stops and gets traders to stop and reverse.
The second center leg rise/fall thriggers the center leg stops.
This second leg ot the M triggers the stops of those traders that have taken short/long positions of the first leg and grabs any breakout traders that have pendig orders above the fist leg peak, but not always and in this case those first leg traders are trapped long and must now sell to get out at a loss