What is happening in market is algo systems trading with huge quantities to hunt SLs. Big banks like goldman sachs. Wells Fargo, DE Shaw , JP Morgan etc . All these have pro traders and Mathematical models to judge the moves and control the movements to some extent. However they also face risks, but their models are efficient to enter and exit in the markets. It is called Hot Money. Similar move came just few minutes back , markets went down . Luckily our SL was not hit , High made was 298 but SL is at 315 , Currently trading at 176. So always keep quantities in control.