Rubicon Project has officially kicked-off its long-expected march toward going public.

The Playa Vista ad tech firm filed an S-1 document with the Securities and Exchange Commission this morning, seeking to raise $100 million on the public markets. There was no stock price or valuation listed in the filing.

Rubicon’s announcement ends a three year drought of L.A. tech companies going public; the last one came in January 2011 with Demand Media.

The company provides an ad exchange platform that connects publishers with advertisers. It was launched in 2007 by a group of local ad tech veterans, including serial entrepreneur Frank Addante, who serves as its chief executive.

It was one of the earlier players in the automation of online ad selling and real time bidding. The ad tech category is dominated by services from Google, Microsoft and AOL, but Rubicon has said its global audience is larger than them all, citing figures from ComScore. In its filing, Rubicon claims it reaches 96 percent of Internet users in the United States and 550 million people worldwide.

The S-1 shows that Rubicon is not profitable. In 2012, the last full year for which information was available, it posted a loss of $2.3 million on revenue of $57 million. The company recorded a loss of $9.2 million through the first nine months of last year, more than twice the $4.3 million it lost in the year-earlier period. Revenue through the first nine months were $55.7 million, up 48 percent from the same period the year earlier.

Addante, 37, is listed as the largest individual shareholder with 10 percent of the company. Santa Monica venture capital firm Clearstone Venture Partners owns 24 percent of the Rubicon, listed under the firm’s Managing Director Sumant Mandal. News Corp. also has 21 percent – a stake it gathered both as an investor and through its sale of its Fox Audience Network to Rubicon in 2010.

The company will be listed on the New York Stock Exchange under the symbol RUBI.