Twitter files for IPO; some analysts value company at $10 billion

Washington PostTwitter files for IPO; some analysts value company at $10 billionWashington PostTwitter announced Thursday that it has filed paperwork to begin the process of become a publicly traded company. The firm made its announcement in a Twitter message at 5 p.m., Eastern. “We've confidentially submitted an S-1 to the SEC for a planned IPO.