[ameribbean expat]

Bullcrap. He probably did it on Berkshire:

“The Balance Sheet reveals that Berkshire Hathaway was ostensibly attractive given the price of 76% of book value. And it turns out that the 1964 balance sheet was in effect missing an important hidden financial asset in terms of available past losses that could be used to eliminate substantial future income taxes. Subsequently, Berkshire did make substantial profits in 1965 and 1966 that benefited greatly from a lack of income taxes. The extent to which Buffett valued the potential use of the past tax losses is unknown.”

http://www.investorsfriend.com/why-warren-buffett-bought-berkshire-hathaway/

[Henchster]

“The Balance Sheet reveals that Berkshire Hathaway was ostensibly attractive given the price of 76% of book value. And it turns out that the 1964 balance sheet was in effect missing an important hidden financial asset in terms of available past losses that could be used to eliminate substantial future income taxes. Subsequently, Berkshire did make substantial profits in 1965 and 1966 that benefited greatly from a lack of income taxes. The extent to which Buffett valued the potential use of the past tax losses is unknown.”

HA! I'm guessing that since Net Operating Loss Carryforward had been recently added to the tax code (1961 or 1962 as I recall) Buffet simply failed to realize he was holding an additional asset!