the nearby oil contract October that expires today is up $20, Nov contract becomes the active front month tomorrow and is only up about $6.  some of that move may be due to the $20 move in the October.  I've seen oil make substantial tops several times on expiration day, got caught in a short squeeze like this once myself, though it wasn't the $20 variety.  I was looking at shorting USO today but it didn't get pulled up that much, trading more in line with November crude.  Could have scalped over a buck though off the short, I expect it will be down more tomorrow.