Options expiration can often exacerbate moves when there is a shock. Shorting volatility has been an easy trade for months on end and the VIX has recently been hanging out around 16. This all leads me to believe that there is a lot of shorting of vol going around.
I want to remind readers that there are now weekly expirations. Those who are short this week's volatility might be forced to cover and exacerbate the selling pressure. While looking out for individual bargains might be a good strategy, keep in mind there is potential for something uglier. The best time to step up and try to catch a falling knife might be the close.