Everyday I see those huge Apple bids at 1.00 from BATS. Are these bids trying to catch mistakes what are their purpose? Skew the volume ? Mess with other algorithms? I never see the opposite say 2 million ask at say 1.000? I wish there was a book I could learn more about market microstructure most of the books out there are mainly "political" motivated they focus if HFT and other things are good or not while I would like to know the algorithms. Any recommendation?