I just saw this, found it interesting and thought I'd pass along...
Just about, since the end of June, if you look at the volume for the day, if it's dips below 71 million, the next day, it rises above it, along with normally a decent gain on the share price as well.
Today's vol was lower than avg at 66 million. From what I see, this theory seems most solid when the trading vol has been above the 71 million level and then comes down...because between Jul 29 and Aug 11 vol was below this threshold.