Joseph Taussig of Taussig Capital wrote a 58 page paper on the "structural alpha" of Berkshire Hathaway and other levered, permanent capital vehicles (reinsurers, insurers, banks and others).
The paper is available on his website:
Warren Buffett, one of the first hedge fund managers:
How can one gain access to this "structural alpha" of low cost leverage and deferred taxation? Buy or build the appropriate structure (such as a reinsurer, insurer, or bank). Several hedge fund firms have done so already.