Comment by calpaterson

Well, I say "more or less" :). But the fact that there is a single global database doesn't mean that you can read every key or value (but generally, yes, you can _read_ everything). I mention in passing prolog-style permission systems for evaluating perms.

But anyway, specific trades are rarely private to one part of the bank for many reasons. For example regulatory: these days you have to notify the regulator about every trade.