Millennial Media, a mobile advertising platform company serving multiple mobile operating systems, registered with the SEC for a $75 million initial public offering on Thursday. The Baltimore, MD based company, which was founded in 2006, booked $88 million in sales for the twelve months ended September 30, 2011. Morgan Stanley, Goldman Sachs and Barclays Capital are the lead underwriters on the deal, for which pricing terms and timing were not disclosed.