greenmonster, I don't know "what the volume was when we hit the low" but...
...just before it fell off the cliff, someone posted that we were on track to do 10M before noon.
I glanced at the volume figure just a few moments before the drop and it was a little over 6 Million.
On the way down there were big gaps in price between some successive trades. It looked like a free fall.
After reading the forums all day I do agree that this was all about the MMs grabbing shares by delibertly targeting the preset stop-loss orders. The MMs were hungry and they needed to be fed.