Berkshire's big day: $24 billion in trading

Warren Buffett's Berkshire Hathaway got a rousing introduction to the S&P 500 this month -- though it wasn't quite the most lavish ever.

Investors bought and sold more than $24 billion worth of Berkshire shares last Friday, the day the stock joined the S&P 500 index of big companies. That is the second-largest single-day volume for a U.S. stock in the past decade, according to a survey of currently listed companies by Capital IQ, a unit of S&P.