Here's a theory, keeping in mind that no explanation can account for everything. There are always many things going on to account for what the price is doing.
If I had a large stake of BTSX and I wanted to get a bunch more.
This looks very appetizing.
So you buy $132,000 worth of bitUSD first. Then Sell your BTSX on the exchanges to push the price down.
If you can push it below .000043 BTC/BTSX ( above 68.68 BTSX/bitUSD) and keep it there for a moment while youve got your orders to sell all the bitUSD you acquired earlier on the BTSX exchange ready to capture all these margin calls.
So long as it takes you less then what you profited from triggering the margin calls to do it( could be as much as 300 BTC worth of BTSX, depending on where you bough bitUSD) you've capture a sizable profit and increased your BTSX holding. As well, now you can buy as much of the BTSX back as you're able at the now depressed prices.