Facebook files for mega-IPO

Facebook filed for its hotly anticipated initial public offering on Wednesday, setting the stage for Silicon Valley's largest-ever IPO.
The world's largest social network, a dorm room project for Harvard dropout Mark Zuckerberg that exploded in popularity and vaulted to Silicon Valley's top tier within 8 years , submitted preliminary IPO documents to the U.S. Securities Exchange Commission after weeks of frenzied speculation.