Would you mind explaining how Bitcoinica is displacing risk to MtGox? Because I don't see how they possibly could. I don't think you understand the risks of margin trading.
Despite the deliberately opaque and complicated way this system is operating, I'll try and explain my concerns as clearly as I can, without knowing more about the inner workings of bitcoinica, it's financial status, how it's trading bot works and how it hedges.
Basically, it all comes down to the fact that it can become very expensive to hedge a leveraged position (i.e. more than the initial deposits), on an exchange that does not allow you to also leverage the hedge position. This is the case we find ourselves in with Bitcoinica and MtGox. One offers leveraged positions but the other does not.
On bitcoinica, you make nominal profits in usd for your trades, not bitcoin. Let's say that I decide to leverage a large bitcoin holding at 2.5:1 on bitcoinica. If I decide that the market is going to move up, and it does, I am entitled to 2.5 times the profit in usd than I would if I were trading directly on the exchange. Where exactly does this cash come from?
Some of it will come from investors who have taken losing opposing positions at bitcoinica, but it is easy to conceive of a huge leveraged position being held for a long time which has accumulated a lot of profit. It is possible that bitcoinica would not have the volume on its own orderbooks alone to pay the winnings. So once the trader closes out his position, bitcoinica may have a significantly acute deficit to meet which may make them insolvent.
When bitcoinica's orderbook becomes internally out of balance, the overspill from any huge positions closing out will require bitcoinica to foot the bill which is denominated in USD. Because bitcoinica does not pay this bill from it's own funds, the money necessarily has to come from the btc deposits on its books. Bitcoinica can 'hedge' the position, but since they can not leverage it, they would have no option but to try and use the bitcoinica depositors bitcoin on mtgox to speculate on the market proper for a profit. Considering the fickle nature of the market, this is very risky and could potentially be a double edged sword for bitcoinica traders.
So bitcoinica now has a strong incentive (almost a requirement) to profit on the MtGox platform. And since they are privy to a hell of a lot of market position data and other market information, they have an unfair level of insight into the market - even if this insight is only coming from a derivative platform as long as there is enough people making predictions it is extremely representative of what is going on in the market proper as everyone is speculating on the primary market itself. So what I am saying is that there is a strong likelihood that zhoutong would be forced to use this data to manipulate traders on the exchanges. Another potential scenario is that he would attempt to minimize the amount to be 'hedged' or put at risk, by actively trading against his clients directly on the bitcoinica platform. Neither scenarios are pretty.
When you consider that a lot of high volume traders are starting to take leveraged positions, you have to wonder how bitcoinica is supposed to foot the bill if a net majority of them happened to wind up significantly in the green at some point in the future.
Also, consider that someone with a lot of capital could take up a large position on bitcoinica using lots of leverage then pop over to MtGox, take a huge bite out of the market, maybe even at a loss, and still wind up hugely in profit because of his bitcoinica position.
Zhou should absolutely NOT publicize the net balance of the order book, because this would allow market manipulators short squeeze his customers much more easily.
Why should zhoutong protect his clients who are taking extremely risky positions at the expense of the market proper? Doesn't sheltering a section of the market participants go against everything the free market is supposed to achieve? People who take risky positions and lose deserve to have their money taken away as they would have been perfectly entitled to the profit had the trade gone the other direction. They should not be trading with more than they can afford to lose.
Why does MtGox or TradeHill not feel the need to do this? Zhou must just value his clients so much more than everyone else. It of course motivated out of self interest. Work your own way through to the logical conclusion of that one.