I have seen this number be way off and not move the market. In my humble opinion, I think this moved the market more because of a move in the futures pits than the number. Let me explain:
Right before the number was released, the s&ps were in a range, I belive 932-933, I don't remember the exact numbers right now but it was a tight range of a point or so. About 45-30 seconds before the number came out, Merrill started buying the hell out of futures contracts, pushed them up at least 2.5 points getting many people long thinking merrill new what the hell he was doing. The number came out way lower than expected and I think the locals punished him and others trying to get out of their long futures sending them down 9 handles from the peak. Stocks followed the same pattern with buying right before the number on the futures spike, lots of bids, and then everyone sold the hell out of everything and punished the longs. Just my opinion, but in the past, this number has been way off and stocks didn't follow it. I think Merrills screwup helped the sell off mostly. Just my two cents. anyways, it was a good down scalp. Moral, always wait for the number before jumping in.