The combined agency, named Wunderman Thompson, will comprise 20,000 staff across 90 countries. Wunderman chief executive Mel Edwards (pictured, left) will lead the company as chief executive, while Tamara Ingram (pictured, right), chief executive of JWT, becomes chairman.

Bringing the businesses together will simplify their services for clients, a number of which are shared by the two agencies, WPP said.

The enlarged agency is being positioned to provide “end-to-end solutions – through creative, data, commerce, consulting and technology services,” according to WPP.

Mark Read, chief executive of WPP, described the merger as a “formidable combination” that combines “the best of JWT and Wunderman in a single agency”.

He said: “Clients want greater simplicity from their partners and this development, like others at WPP, is designed to reshape our company around their needs.”

The merger allows WPP to “compete more effectively in the sectors with the most significant opportunities for future growth,” Read added.

The move comes as WPP looks to streamline its portfolio of businesses and pay down debt, a strategy which has seen the company sell off its stakes in Globant and AppNexus and review its ownership of Kantar. In September, the company merged VML and Y&R.

The combined business will be operational from early next year.