With the market range-bound for many weeks despite the unfolding European crisis one has to suspect that market players were positioned for range-trading via the options markets.
So long as the market remains range-bound, all is well. The trouble comes when the market breaks out of ranges and becomes directional. They then have to sell spot in a big way.
When markets break out of long-term ranges like today you also tend to see panic-hedging from corporate treasurers. Given that we are only a bit more than two weeks until the end of the year, the selling is likely even more intense than usual.
