The Risk of a Bubble in the Market

If Mr. Market goes in the depressed phase that Berkshire Hathaway has got an investment portion of its book value about 28,000 per class A share, that would put the Berkshire Hathaway share much lower than what it is now. Would Berkshire Hathaway consider buying back its own share or has it done its own past or is it out of the question? If the market went in the tank, Berkshire stock would go in the tank too. It wouldn't bother me because we would have very intelligent things to do with whatever capital we came into.