Huh? there is no magic to that or collusion. MMs are required to post there best bid and ask. If the best ask is 500,000 shares, it doesn't mean that there are not already several other offers lined up for 600,000, 700,000 or a million shares or 10 Million shares.
Thats why when people say "Its a fake wall," or the "Wall is thin," its just babbling nonsense.
News 
Market Data 
Discover 
