the reason i care about "why" is that a theory about a "mysterious major seller" is really bearish and doesn't square at all with the fundamentals as we know it. i.e., if somone is willing to let go of this many shares imo we'd see lots of others liquidating too, and the tape doesn't suggest this at all.
in fact, we see just the opposite down here: accumulation.
sure, we'll go up when PERT's charade is over, but the sad part is retail is so demoralized right now that it will be institutional investors who grab most of the low hanging fruit this time around. jmho.