Actually, I believe the 0.01 prices for $40 stocks were due to some sort of computer glitch at the exchanges. Not even trading bots are dumb enough to sell $40 stocks for a penny.
May be you are right. May be this was a glitch and they actually acted right and in the interest of the fair market. My initial reaction was to remember that these are the same regulators that banned short selling in 2008. Next time they can ban market orders and stop orders...
I think that a lot of the debate here is disagreement over what's defined and what isn't. Clearly, the rule itself is defined, as are the guidelines, but specific bust rulings need not follow the guidelines. This becomes empirically clear when one exchange busts a trade of a certain category, while the other does not. Committees at each exchange decide how to apply the guidelines, and they don't always agree, even when confronted with the same trade price at the same time. It seems to me that if the cutoff applied had been 10%, the OP would not have suffered any loss. That's one problem with "guidelines" instead of "rules". The rules are clearly defined, yes, but they're dictated by guidelines that are not strictly followed, and this cost the OP his/her entire account. As I mentioned earlier, the situation is far better than it was a few years ago, when each exchange had its own rules/guidelines, and it seemed to me that people were actually placing bustable trades on purpose; abuse of the system as such seems much more difficult now. What I find amusing about this is that these "clearly defined rules" contain an obvious misuse of "then" in place of "than". I am against "grammar policing" in online forums, but for "clearly defined" rules such as these I'd think they'd at least get the word usage correct. Oh well, I guess we're all only human.
But stoploss orders are dumb enough to sell a $40 at a penny. If you are a big HFT shop, you are going to use multiple servers, at multiple locations, on multiple exchanges, through multiple brokers. You decide to manually pull the plug on your computers, and as you are unwinding positions, you have to sell to close, buy to close, and remove emergency stoplosses. At any given time, you might have a 100,000 share position on each of 1000 instruments, quite possibly on both sides (you might be both long and short on the same stock as you exploit the bid/ask spread between different exchanges). You will be entering very tight staged stoplosses, to protect your capital in case one of your servers shits the bed with an open postion. As you unwind, closing the positions get out of sync with removing the corresponding stoploss. And bam they get hit before they cancel, you're in a position you did not want. "Shutting off the switch" is easy. Unwinding to flat so you have no exposure at all could be tricky, and easily take minutes even with a completely automated "go flat" switch.
Your plan then puts the exchange in the market and subject to losses, not just for any one account but for any trades that they have to eat. That simply wouldn't work out. You can't put the exchange in a position to go bust.
How is that a hedge? If I am long stock, how is going long futures a hedge? To be hedged you go long one thing and short another.
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