AutoTrader Group, the Atlanta-based operator of the AutoTrader.com online automotive marketplace, has taken initial steps to go public, the company announced Friday.

AutoTrader Group would likely be the largest initial public offering by a Georgia company since insurance and Duluth-based financial services firm Primerica spun off from Citigroup in 2010.

The company filed a registration statement for an IPO, or initial public offering of stock, with the Securities and Exchange Commission on Friday after markets closed.

It is not yet clear when the company intends to start public trading of its stock, but the filing states that it is seeking to raise up to $300 million. Proceeds will be used to pay off some debt and for “other general corporate purposes,” it said.

The company said in the filing it expects its stock to be listed on the New York Stock Exchange or NASDAQ under the symbol “ATG.”

AutoTrader Group is majority owned by Atlanta-based Cox Enterprises, parent company of The Atlanta Journal-Constitution. Providence Equity Partners and Kleiner Perkins Caufield & Byers are other major owners of AutoTrader Group.

A spokesman for AutoTrader Group declined to comment, citing securities rules.

AutoTrader.com touts itself as “the Internet’s largest auto classified marketplace.” The site brings car dealers and private sellers together with buyers and also has shopping and research information.

AutoTrader Group also operates vehicle valuation firm Kelley Blue Book, which was acquired in 2010, and various automotive sales and inventory software companies.

Combined, AutoTrader Group’s various websites averaged more than 29 million unique users per month, the registration filing said.

AutoTrader Group reported revenue of $1.03 billion in 2011, up 38.5 percent from 2010. Net income was $68.1 million last year, up 38.5 percent from 2010. For the first quarter of 2012, revenue climbed 12.5 percent to $273.5 million compared to the first quarter of 2011, but net income dipped by more than a third to $10.2 million.

Much of the company’s growth in recent years has been through acquisitions -- last year it bought VinSolutions, which develops software for car dealers -- but it has also seen internal growth, according to the filing.

AutoTrader Group, based near Perimeter Mall, was founded in 1997 and has 3,200 employees nationwide.