Easy explanation. Some ignorant chump put in an order to sell a large block at the market. In pinkie land anything goes. I saw it. It went down and that last chunk of the trade went through at .0021, and then the Bid and Ask popped back in at .0023 and .0025. Can't feel sorry for anyone who is that ignorant.
That was a double print, gmjones. VFIN sold 665k at .0025 and then printed .0021 to the seller. VFIN made the spread for the trade and broker gets commision on the gross sale at .0025. Happens all the time. VFIN commits grand larceny and the seller gets screwed for double commission.