Advertising mogul Martin Sorrell said Wednesday that if Disney completes its deal for Twenty-First Century Fox assets, it would represent a clear top media investment for his company.

A Disney-Twenty-First Century Fox deal, which could be announced as early as Thursday, would have an enterprise value of $60 billion, sources told CNBC. Disney became the sole suitor after Comcast, parent of CNBC, dropped its bid Monday.

"If Disney comes together with Fox, Disney and Fox would be a clear No. 2," said Sorrell, CEO of WPP, the world's largest advertising group, of his company's biggest media investments. He said his firm's two largest such investments currently are Google and Facebook.



"Google would be a clear No. 1. Facebook three. But absent that deal, Facebook would move up to No. 2 as media destinations for us in our media book," Sorrell said in an interview on CNBC's "Squawk on the Street."

Earlier this year, Sorrell said his company was poised to increase its investment in Facebook to "well over" $2 billion this year," while keeping Google as its top investment in 2017.

"Google ranks No. 1 in terms of the destinations of our media investments. Facebook ranks third (but) may this year actually become second," he said in August.