The share price drops when people sell at market. I literally NEVER sell at market unless I am exiting the stock entirely. But someone with enough shares to affect share price is selling at market.
That plays into the MM hands, who can buy them cheap by dropping their bid after each tranche.
If you look at any MM's spread, there is a bid, an offer, and an amount. They MUST buy or sell at their spread, but only for that amount. THEN, they can drop their spread and buy another tranche, then repeat. And they can change the quantity as well. And, they have to do it fast enough that they 'beat' other MM's doing the same thing. This is why, when you sell at market, they are all sold immediately, but if you look at the tranches, you will see that they continuously drop in what they pay you.
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