Going into EOM a big order (either way, though usually on the sell side) can certainly precipitate people bailing out.
I love to put in lowball orders going into EOM or (better) EOQ or (even better) EOY. Maybe only 1 in 5 or 1 in 10 fills, but those fills can be GREAT fills.
So when you are putting in your 80k sell order at the same time you are scooping up shares on the bid, do you actually have the shares to sell, or is that basically a bluff with no shares (i.e., a potential naked short)?