Their negative accounts are usually closed out and losses deducted from a segregated account that has the performance bond in a safe yielding T-note. I know a few traders down here who withdraw every week and go negative on the next Monday just make it up (or try to) by the end of the week. If it is prolonged, they'll take it from the performance bond account. Some that clear through RCG and Alaron generally are allowed to do this, as long as they've been on the floor for awhile.