Facebook, the world's biggest social media website, will begin its eagerly awaited first day as a publicly traded company today. Stock in the California-based company will sell for 38 dollar a share when trading begins on the Nasdaq Stock Exchange. The initial public offering, the opening price at which investors can buy a share, is expected to raise about 16 billion dollars, making it one of biggest stock debuts in U.S. corporate history. The stock offering has driven Facebook's value to at least $104 billion, making it one of the most valuable U.S. companies. Facebook's chief executive, Mark Zuckerberg, aged 28, started the popular social networking site just eight years ago in his college dorm room at Harvard.