This post is a reminder that we are in a market dominated by hedge funds. While they don't control as much assets as pension funds or mutual funds their exposure jumps around a whole lot more so they are the marginal investor moving prices around.
When the market goes down they "de-risk" as a group in fear of having too large a draw down. When the market rallies they rush to put exposure back on in fear of missing out. They are reactive. This type of behavior causes extreme moves.
Both moves higher and lower seem endless as this strategy, if you can call it a strategy, amplifies momentum. As long as hedge funds as a group continue to act like chickens with their heads cut off it is prudent to allow for larger market moves than would be usual.