Someone wanted to sell 350,000 shares today. So he made a deal with the market maker (BMAK). Usually it's at a significant discount because you can't sell that many shares for yesterday's price. Other factors play a role, like liquidity etc. Anyway, 0.463 is a good price for the seller.
BMAK starts shorting the stock until he sells a total of 350,000 shares. Then, he covers by buying the shares from the person who wanted to sell those shares initially, which is why you are seeing those big blocks show up. And then, BMAK backs off immediately, so we know it is him. We know this for a fact.
This is how this works. Someone explained it to me 2 years ago. Although these big trades usually occur after the market closes. I guess they want to give SIAF some room to recover. Whatever BMAK shorted higher than 0.463 is profit for providing the service.
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