Most financial institutions operate as a black box in that regard. Until you actually withdraw something, you know nothing about the internals or where your money / security may really be.
From a programming perspective, it doesn't really make any sense to make real Bitcoin network transactions for every buy and sell order; an internal database can keep track of all that way better. Arguably, they could steal all your Bitcoins if they wanted to anyway, so it doesn't really matter how they handle the internals.
From a programming perspective, it doesn't really make any sense to make real Bitcoin network transactions for every buy and sell order; an internal database can keep track of all that way better. Arguably, they could steal all your Bitcoins if they wanted to anyway, so it doesn't really matter how they handle the internals.