Berkshire's 25% Plunge Has Buffett Bulls Screaming 'Buy'

Warren Buffett's Berkshire Hathaway hit a new milestone today (Monday) in a descent that had already put the stock into a 'bear market.'

The class A shares closed exactly 25 percent below the all-time high set last December.

Today's closing price of $111,900 each is the lowest for the stock since August 15, almost one year ago.

Berkshire is down 21.0 percent in 2008, underperforming the benchmark S&P 500 stock index, which has dropped 15.9 percent this year.

While Doug Kass, who has been vocally shorting Berkshire over the last few months, is presumably celebrating, some long-time Buffett bulls see an increasingly ripe buying opportunity.

This morning on CNBC's Squawk Box, two of them made their case in a segment with Carl Quintanilla.

Andrew Kilpatrick, who wrote the Buffett book Of Permanent Value, concedes that Berkshire is having a "tough year" amid weakness in the housing and insurance markets. But he expects Buffett "will wind up doing better than most" due to the strength of his balance sheet.

Whitney Tilson, of T2 Partners, argues that while there are "short-term headwinds", Buffett will be able to take advantage of the current "weak and choatic" environment. He sees a substantial increase in the liklihood Buffett will use his big cash holdings to do a "transformative" deal. While Tilson would like to see Berkshire buy American Express outright, he doesn't think that particular deal is likely.

Current Berkshire stock prices:

Class A:

Class B:

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