There's an article that describes it from a retired MM. I'll try to find it.
Basically, what happens is that a market maker gets a buy or sell order from a big broker. If the MM doesn't fill the order, it is less likely that the broker will call them next time an order needs to get filled.
So, they almost never have the actual shares in treasury and borrow the shares to fill the order. Their next task is to find real shares and quickly cover the short. They do this by doing things like buying shares from stop orders on L2 and covering the short and keeping the difference.
If the stock spikes suddenly, they are temporarily in a world of hurt and need to drive the ask back down so they can buy cheaper shares and cover the short. If they can't, they lose money, so they will try all kinds of tricks to snap up shares on the ask, including launching hit pieces (which Seeking Alpha has been found guilty of doing,) or launching a huge short position and flooding the ask until it gets to the point where they can cover the original position. Remember, they make money by shorting the stock and break even by covering the original short position.
What I'm looking into now is how this plays out during the two week period during which the SEC allows them to cover the short.
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