Facebook, Inc. held its initial public offering (IPO) in February 2012, and began selling stock to the public three months later, reaching an original peak market capitalization of $104 billion. On July 13, 2015, Facebook became the fastest company in the Standard & Poor's 500 Index to reach a market cap of $250 billion.[12] Facebook has more than 1.65 billion monthly active users as of March 31, 2016.[13] As of April 2016, Facebook was the most popular social networking site in the world, based on the number of active user accounts.