The Internet, is by design, a public, insecure network that's being used every day for extremely sensitive and critical information.
That's a serious problem waiting to happen. If something happened that creamed the Internet (it CAN happen!!), think of how screwed the corporations/stock companies/etc. would be.
Maybe my solution isn't the best one. I'm proposing ideas, not coming up with a final solution. How would you suggest implementing a secure network for these types of things?