My understanding of how market makers maneuver is that they strive to close each market session net neutral through stockholdings or hedging.It is also possible that a lot of share inventory is sitting in Market Maker hands. They will unload once they see a catalyst to tic the bid upwards, because they know this is oversold and is over due for a surge just on technical basis.
A MM would have a difficult time financially being short a million shares and with news the stock opens up 20%.
MM make money on trading volume and not speculating on price movement.