Warren Buffett passing on purchasing shares of Berkshire's stock when his company's cash pile is sitting at a record high ($325 billion) signifies that one of Wall Street's most ardent value investors is struggling to find a good deal. Berkshire's price-to-book value recently hit levels that haven't been consistently observed since 2008.

Buffett hasn't aggressively bought many stocks this year but spent $2.9 billion buying shares of one company. The reason behind his biggest investment is simple: He believed the price was right. Even Buffett doesn't seem to think this stock is a no-brainer buy now,