Subject: Re: Are Berkshire Shares Safe?
"I am not sure I understand the distinction between margin and cash accounts when it comes to safety in the event of a broker going bankrupt. Is this also the case for a margin account with no margin balance outstanding?"

I have not studied this in depth, but my understanding is that if you have a margin account, your securities can be lent out. I am not sure if this can only occur if you have a margin balance outstanding. I have never used margin.