You question how GRN's intrinsic value can be calculated merely by dividing its $24 bil. float by its number of shares outstanding, 76.5 mil. You think it's inevitable that a megadisaster will hit and Buffett/GRN will have to pay out some of its floate as underwriting loss. But you neither understand Buffett's insurance strategy nor reinsurance. If you look at the 1997 shareholder letter, you will see that for most years Buffett has been in business, he's hardly ever had to pay out very much of his float to cover claims. For the last three years in fact, he'd had to pay "less than %1." Buffett even refers to his float as a "cost-free source of funds." It is because Buffett is so skillful at keeping underwriting losses to a minimum that he could build up a multi-billion dollar float over the years and invest that float in the stock market at a huge returns. One way Buffett bought GRN is because its business is reinsurance. Reinsurance is inherently less risky than insurance because risks have already been vetted once by the primary insurers before ever having to be covered by the reinsurer. Reinsurers hardly ever have to pay out their float as a result. And because Buffett's reinsurance is designed to cover megadisasters (which rarely happen if ever) rather than less disasters (which happen much more frequently), Buffett hardly ever has to pay out his float. California just gave him $500 million 2 years ago to insure against "the Big One" but Buffett hasn't had to pay a cent of that back and he's used that to invest in stocks in the meantime. And even if "the Big One" happens, the primary insurance companies will take the big hit, while Buffett says his "worst case" cost for the "Big One" is probably around $1 billion, which Berkshire can easily absorb.