European vs American doesn't matter -- what's important and exceptional about his short vol position is the lenient margin requirements.
Buffett's counterparties are allowing his positions to go underwater, to the point where mere mortals would have been "asked" to put up more collateral or liquidated. European options won't get exercised on you, but they still trade, and brokers can and will subject them to margin calls.
thx, i should have read the original post on this subject more carefully. he is short the european style options therefore being subject to margin calls.
If you had plenty of free margin then file an IB complaint ticket (instructions are on their web site). If they eventually refuse and you still believe you are correct then you can file an NFA arbitration. I would not worry about counterclaim - that mainly arises I think if they lost money on your account(e.g. account went to debit balance). I would claim that they should have looked at the spot rate for non-deliverable forwards on the Yuan. I think they do. Maybe they did - you need to go back and see - maybe there was a jump in the forward at that time also.
I'm sorry for your loss, but stories like this reassure me that IB is on top of things, that my money is safe there, and that I'm not exposed to the risks of other customers trading with excessive leverage and/or in illiquid markets subject to black swans.
I do not think they should use market orders to liquidate in illiquid markets where there is no reasonable bid and ask. Instead, they should start with a limit order and gradually move it out. If necessary, they can move the limit out quickly but I do not think they should *start* with market orders. This can all be done under automation. 99% of the time a reasonable limit order will be filled promptly if the order can be arbitraged against underlying or another month etc. by someone somewhere at a $50 or $100 profit, even in relatively illiquid markets. Also for currencies they should of course take into account bid and ask in other months. The renminbi future is not really all that illiquid since it can be readily arbitraged against the spot non-deliverable forward market, which is usually liquid enough. Go through their *formal* complaint procedure and then file an arbitration if need be.
Why trade such an illiquid market in the first place. I wouldnt touch these things with a 10 ft pole. There are ETFs with which such problems would have been avoided. How is IB supposed to mark such positions? Theres a bid and theres an offer (if at all), and thats that. Using some EOD quote is in my opinion ineffective. IB should add CNY NDFs to IdealPro. That would be the most appropriate instrument for this purpose.