Realogy Corp.'s parent company, Domus Holdings, which operates Century 21 and Coldwell Banker, filed to raise as much as $1 billion in an initial public offering in order to shed its heavy debt.

Preliminary documents filed Friday with the Securities and Exchange Commission by the company do not say the number of shares to be offered or the price of the shares. According to the filing, there is no guideance for the proposed price-per-share, nor is the potential stock ticker or market listed.

The company, owned by Apollo Group and Paulson & Co., currently has $7.23 billion in debt, but plans to reduce that to almost $4 billion after the offering. The company also plans to cash in on almost $2 billion in convertible notes held by Apollo and Paulson.

In 2011, Domus' revenue was at $4.09 billion. 2011 losses grew substantially from the year before to $441 million from 2010's $99 million. Pointing to data released by the National Association of Realtors on sales of previously owned homes, the company said it expects the housing market to pick up and their numbers to pick up with it.

The company's revenue comes from royalty fees received from its franchisees and are based on a percentage of their sales commissions.

In addition to Coldwell Banker and Century 21, Realogy also operates Better Homes and Gardens Real Estate, ERA and Sotheby's International Realty.

At the end of March, the franchise system operated about 13,800 offices around the world.