There are roughly 30 million BTS worth of bitUSD margin called right now. At current prices thats about 2 milion USD. According to the state of the network report from september 5 there have been 5 million bitUSD in circulation at BTS price of 0,12-0,16 USD per BTS. The math says that it could be that half or even more of all bitUSD are margin called. What a profound test of the stability system!
UPDATE 14:03 CET: now there are 130 million BTS margin called for bitCNY. At prices from september 5 thats all bitCNY.
Since it seems that the margin calls are getting absorbed by the market, the question is who is taking the risk. Watching the decline today, I'm coming to the opinion that the stability system is prone to external factors: as long as people are afraid of bitcoin tanking, they do not believe in BTS price having found a bottom. No matter how low the price went, when BTC takes a 20 % hit, BTS will take at least 30% hit. So despite the big losses they keep selling BTS down in USD value.
Even if the margin call prices are low, people still jump in the order book to sell slightly lower than that and get rid of their BTS. Thus the stability system drives down Bitshares market cap.
Since the stability system is designed for 24 hours losses of at maximum 50%, we could witness the liquidation of all smartcoins today. The so called black swan event. But it also looks like someone with deep pockets will prevent that from happening.
UPDATE 14:13 CET: 46 million BTS margin called for bitUSD