Summary: Facebook CEO and founder Mark Zuckerberg is selling 41.4 million shares of Facebook stock that are worth about $2.3 billion. He will use the money to pay a tax bill related to his exercising an option to buy 60 million Class B shares. The transaction is related to Facebook's secondary offering of 70 million Class A shares. The shares are going to be offered primarily to index funds now that Facebook will be a part of the S&P 500 as of the close of trading on December 20.
