Wish I knew. I'm long crude, and I use OIH puts as a hedge for that (as well as to benefit from any overall market decline, which often affects the OIH components). I had some puts in other stocks, which I closed out gradually yesterday and was actually up for the day... until the last hour. Between 14:50 and the close, the Dow and the S&P dropped another .75%, oil dropped 80 cents, but OIH, after a dip, actually went up.