Travelport, the travel-booking system Blackstone Group BX bought eight years ago, is ready for its public debut.

The Atlanta-based marketplace used by travel agents to book flights, rental cars, and hotels filed for an initial public offering Wednesday with a placeholder sum of $100 million, an initial figure used to calculate costs that may change.

Travelport, which reported a net income loss of $207 million last year on more than $2 billion in revenues, could raise about $500 million in the offering, according to a Bloomberg News report.

Travelport initially tried to list in London in 2010, but its plans were waylaid due to the debt crisis in Europe. The company has struggled to turn an annual profit since 2011 and plans to use the IPO funds raised to pay down part of its debt. Travelport reported almost $3.4 billion in long-term debt as of March 31.

Blackstone initially invested $4.3 billion in the travel platform in 2006. The filing didn’t specify the percentage of shares the private equity firm holds. Other investors include Technology Crossover Ventures, One Equity Partners, and Morgan Stanley.

Morgan Stanley is managing the listing, which will use the ticker symbol TVPT. The company has not specified on which exchange it will list.