I've seen it in Russia. They explained it to me that it is only a technical issue, and the stock only briefly had a negative value anyways, so why am I asking all these questions?! That's why you should not trade third world stock markets directly. Also, I heard about negative stock value in China, but I didn't see that, so I dunno. But I've seen negative prime rate in Japan, too, so I reckon, nothing is impossible...
Really! I know that other brokers have allowed futures trading in IRA's usually through some kind of intermediary. I don't know how that works and i am a bit puzzled because if you're short a future it would seem to represent a position with undefined risk. I wouldn't want to trade futures in an IRA unless i could be both short and long. I checked the TOS web site. They still indicate no futures trading in IRA's and no positions with undefined risk such as naked short calls. I guess they just haven't updated their site yet.
one way you could do it is sell a bear call spread at the money. which gives u an almost 1:1 Profit /Loss situation which you could derive with shorting the stock. I have done that many times in my IRA the trick is expiry. and if the short leg is to be assigned then they can unilaterally close the position at 355pm the friday of expiry. last options expiration in tradeking . they over looked it and I was short shares of AAPL JWN and COH.. then on Mon mornning I quickly closed AAPL. and wanted to watch the fun.. around 2 pm. I got a call from Tradeking that they have unilaterally closed the other 2 positions.. ha ha.