Sullivan & Cromwell has represented travel website owner Priceline Group on its $500 million investment in Chinese online travel company Ctrip.com, which turned to Skadden, Arps, Slate, Meagher & Flom for legal advice.

The investment, through a convertible bond, expands an existing commercial agreement between the online travel firms. Customers of both firms can select from Priceline’s offering of 500,000 hotel options outside Greater China, and Ctrip’s portfolio of 100,000 in Greater China.

The Skadden team that advised Ctrip was led by Hong Kong corporate partners Julie Gao and Jonathan Stone, alongside New York technology partner Stuart Levi and Los Angeles corporate partner Michael Gissier.

Sullivan & Cromwell acted as U.S. counsel to Priceline, and was led by New York partners Brian Hamilton and Keith Pagnani, and Beijing partner Garth Bray. Maples and Calder advised the Chinese company on Cayman Islands law.

Shares from the convertible bond, together with an agreement that allows Priceline to purchase Ctrip’s shares on the open market, would see the world’s largest online travel service provider own up to 10 percent of Ctrip.

The purchase of the convertible bond also allows Priceline to appoint an observer to Ctrip’s board.