This was a FORM T trade which means you do not see the volume from it until after close. Basically the order comes in and the market makers want to fill it but dont want the price to drastically move at one time so they fill the order with there reserve of shares which wont show up as volume at all or fill it in increments on the open market and then print the average after the close.
All depends on the buy orders. If there are matching orders they can be sold at one time. If not, they are sold in increments. I have sold penny stocks a million shares at a time and sub-pen. at 100 million shares at one time. The idea is to not flood the market to maximize price received.
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