A word of caution: Warren Buffet did not become the richest man in the world by allowing his companies to loose beyond a point where his entire fortune is jeopardised.
Supposedly all of NetJets is now profitalble, but should it become necessary to shut down operations (that would take some time of constant losses without a doubt - another 9/11 springs to mind), Mrs Absolutely Loaded can STILL use that as a tax write off and wouldn't loose a dime - even though it might show up on a different position on the tax return: moved from "business expense" to "loss resulting from business investment"
