WPP-Grey Global merger 'on hold'

WPP chief Sir Martin Sorrell has overseen rapid expansion

Advertising giant WPP's $1.3bn (£726m) purchase of Grey Global has been put on hold after files submitted to EU regulators were found to be incomplete.

WPP won the auction for Grey Global, the world's seventh-largest advertiser, having bid against France's Havas and a US private equity firm in September.

UK-based WPP will now refile the merger notification and it will need to wait a further month for approval.

The deal looks set to create a rival to current sector leader Omnicom.

Under the deal, WPP will pay half the purchase price in cash, and the other half in shares.

Grey Global's clients include blue-chip firms such as Procter & Gamble, the world's largest advertiser.

WPP has expanded rapidly in recent years by buying up firms such as Ogilvy & Mather and Cordiant Communications.