If 30 to 35 million shares had been sold by a large seller, there would have been tracks in the form of SEC filings. There are not. That leaves three possibilities. Naked shorts who are either selling more shares or are "walking it down" by selling to each other, making it appear that 30 million shares have been sold when they haven't. This strategy could be or is being frustrated by a big buyer sucking up shares.
Second, massive tax loss selling which is possible since the year has been very good in other stocks. If so that will be over on Tuesday.
Third, many small holders getting frustrated and selling. This is unlikely, since as we have seen in the last few days, some market player is trying to run stops and is being unsuccessful.
My bet is on the naked shorters. There was a general acknowledgement that there were naked shorts before the run up in numbers that would prevent covering. This is a common activity of MMs and hedge funds in low priced stocks which they assume will have to have an equity raise. I think it is likely that they never even look at the fundamentals at that early point and in this case were stuck, and have stayed stuck.
I realize this is a bit of a conspiracy theory, but nothing else really makes sense.