Cleary Gottlieb Steen & Hamilton, Linklaters and Dechert are among a host of firms to have landed roles on an American Express (Amex) joint venture with an investment group led by Certares.

The group of investors will pay $900m (£543m) for a 50% stake in Amex's Global Business Travel (GBT) division, which will be separated into a dedicated holding structure. American Express will also have a 50% stake.

Investors in the Certares-led group includes Qatar Investment Authority through its wholly-owned subsidiary Qatar Holding, funds managed by BlackRock, Certares itself and Macquarie Capital.

Cleary Gottlieb advised Amex on the deal fielding a team out of New York led by M&A partner Paul Shim. In the UK London partner Tihir Sarkar handled the separation and restructuring process to carve out the GBT division into a joint venture. The antitrust aspects of the deal were handled by Brussels/London partner Romano Subiotto.

Linklaters advised Qatar Holding, led by New York partner Tom McGrath.
Other advisers included Dechert for the Certares investor group, Ropes & Gray for BlackRock and Willkie Farr & Gallagher to Macquarie Capital.

Bill Glenn, former President of global commercial services at Amex, will be President and CEO of the joint venture, while Certares founder Greg O'Hara will serve as chairman.

Glenn said: "To our knowledge, this would be the largest single investment made in a travel management company. We believe it will accelerate our growth by funding meaningful advances in technology, analytics and service excellence that will benefit suppliers, partners and our global customer base."

Amex expects to complete the transaction in the second quarter of 2014.

GBT has more than 14,000 employees and generates more than $19bn in corporate travel spending.