all very plausible theories
i like the signalling idea which leads to the rest
i don't know much about the high tech trading
but i would assume so many little trades automatically ring bells and/or set off alerts
and messages are relayed and then relayed to the big boys
to keep them several layers away from direct knowlege of whats happening so they can swoop in and buy up cheap shares before " ? "

as to what it all means:
no one does all this without something to gain!
so we are back to: this has to be some sort sign that something huge is up

how's that for a theory after a little too much coffee this am  lol