Spare a thought for Warren Buffett, who lost nearly $1 billion on IBM on Monday and another $1 billion on Coke on Tuesday. On Monday Buffett lost nearly $1 billion on his third-largest investment, IBM , after the company posted disappointing earnings. On Tuesday, Coca-Cola did the same thing , posting third-quarter revenue that fell short of expectations and warning of currency headwinds. Coke is Buffett's second-largest investment and has been one of the stalwarts of his portfolio for decades. (He left Coke's board in 2006 and his son Howard took a board seat there in 2010). With 400 million shares, Tuesday's ... (full story)