What would happen if I had been daytrading and short on SPY on DEC 18 2014 when there was a relatively quick spike? Lets say I had margined my account 3x (as it was daytrading). I don't have the daily data on this computer, but I imagine it was a very quick (seconds?) spike? What would happen if there's a fatfinger effect on SPY? I'm asking because it seems to me that daytrading something like SPY or TNA with a careful risk strategy is safe from black swan effects, but if I'm leveraged 3x and it fatfingers the wrong way...