What does a negative market cap mean?

Question

Like Berkshire Hathaway has a negative market cap ? I don't understand.

Answer 1

http://finance.yahoo.com/q?s=brka

I think you got the wrong information. According to Yahoo, BRK-A Market Cap is 173.57B:

Market capitalization, or market cap, is a measurement of corporate or economic size equal to the stock price times the number of shares outstanding of a public company. As owning stock represents owning the company, including all its assets, capitalization represents the public opinion of a company's net worth and is a determining factor in stock valuation.

There is no way that BRK-A is worth negative ($112,200.00 per share on closing August 9th) or the number of outstanding share is negative.

Someone probably got their math/accounting incorrect computed.