I notice that sometimes the crude oil futures trade as if they are an oil stock. For example, friday SLB and HAL have blow out numbers and are up huge sending all oil stock indices and stocks soaring. I don't think its a coincidence that the price of crude also staged a big rally. My guess is that many players are arbing oil stocks versus crude futures. So when money flows into one it can support the other and vice versa. I've noticed on other days when oil stocks are taken down by what appears to be s&p sell programs a few moments later weakness materializes in oil futures. My guess is people start selling crude against oil stock longs that have dropped in price. So i guess what i'm getting as is not only does price of crude move oil stocks...but it seems that oil stocks can move crude as well. Then there are days where there is aboslutely no correlation between crude and the stocks. So go figure.