Of these position, only the added positions in Kraft and Burlington Northern Sante Fe were large enough to generate any interest on the buy side, and even then, they were adding to already existing positions.

So what is an investor to do? Barron's does provide some guidance by referring to an analysis by the hedge fund T2 Partners. T2 highlights that the intrinsic value of Berkshire has continued to grow steadily and significantly over the last few years. From Barrons:

Meanwhile, for a truly big company -- with a market cap of $190 billion, total assets at last count of $281 billion, total equity of $119 billion and book value per share of $77,014 -- it has been enjoying quite impressive growth, especially where it really counts. The value of investments per share has climbed to $90,343 in 2007, from $52,507 five years earlier; during this stretch, pretax earnings per share, excluding investment income, has quadrupled from the $1,479 posted in '02; and intrinsic value -- which T2 calculates as investments per share, plus 12 times earnings per share excluding investment income -- at the end of last year ran somewhere between $156,300 and $158,700 a share, or comfortably more than double '02's $70,000.

As a result, T2 believes that Berkshire is undervalued by approximately 20%. Furthermore, if you are to assuming a 10% growth rate for the intrinsic value of the company, which is not speculative for Berkshire by any measure, with a business and cash buildup of $6,000 per share over the next year, the total intrinsic value could approach $178,700 per share. Given the current price, this represents a 46% premium on the stock. Going out further to two years, the number approaches $200,000. While short-sellers like Kass will continue to short Berkshire, and give good explanations - such as Buffett's age and lack of a visible succession plan, new hedge-fund competition, new uncharacteristic exposure to derivatives, and waining benefits from the insurance industry - it is difficult to bet against someone with so much cash to deploy, as well as a track record for wisely putting it to work. While the stock has been volatile, and is receiving attention from the short side, it is difficult for many investors to sell at these levels until more of the issues that Kass describes come to light. For the time being, most of the current long investors will no doubt hold, and look for others to join in - maybe in October.