That all depends on which state said debtor resides. If you have a house.... make sure your wife's name is on the deed too. That pretty much makes keeping your home out of judgements levied against you bullet-proof. Might be hard to do ex post facto though. If all else fails...max out every credit line you have on Bitcoin and skip town.
You must be one of those professional traders? For us mom and pop retails, our brokers will not let us get to that point. For sure not Schwab who I have been with for 20 years and I always got margin calls as soon as accounts dipped below margins requirement. They are always in the position to liquidate my account before me owing them money?
Yes, they will get a judgement which will follow you around and attach assets if and when they appear. BK is the only way out of that trap....or changing your name and moving to Uzbekistan.
A margin account is required only if you write options... because in theory your risk is unlimited. Even if its a multi-leg strategy with limited risk. Purchases of puts/calls however come directly from, and are limited to, the cash side of your account. I assume thats basically because with an option you can lose 100%, whereas with stocks they can define a reasonable margin risk.