Also, because Berkshire is a conglomerate, businesses which generate large amounts of cash (e.g., insurance float, or businesses that would pay dividends if they were a stand-alone companies) can be used to fund capital-intensive businesses (railroads, energy companies, etc.) without paying taxes to move the money from business A to business B, because they're all owned by the same legal entity. Don't underestimate the power of this effect. It is not possible to achieve with an index fund.