Actually, if you incorporate the illegal position within these numbers, you will find that these numbers are fairly close in explaining activity (though there is a margin of error albeit a slight one). That will require some research since the practice is illegal. But, that does not mean it is not a reality or that finding the info to explain how this happens works.
Those numbers reflect the shorting of the VDSC stock.
Says right here they have short positions. Whats your point?
As part of making a market, they may have periodic short positions throughout a trading day if they fill buy orders for more shares than they have in inventory, but they also often have inventory when they fill sell orders. Having an inventory does not mean that they are going "long" any more than having a temporary net short position is "shorting." This kind of temporary short position is legal and necessary for efficient trading. The grey market shows how trades work when MMs don't make a market.
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