NEW YORK (TheStreet) -- There may be more deals to come in the media space following this week's sale of the Financial Times, said Martin Sorrell, CEO of the advertising firm WPP.  

Pearson (PSOsold the Financial Times (FT) to Nikkei for $1.3 billion.

"There's some stresses and strains, particularly in the area of legacy media," said Sorrell, who pointed to tepid growth and a lack of pricing power. "Clearly some of the traditional legacy media owners are feeling the pressure."

In the case of Pearson, Sorrell said the company couldn't sufficiently invest in the FT. Days after the FT deal, there were reports that Comcast  (CMCSA - Get Report) is looking at making investments in several new media companies, which Sorrell said didn't surprise him.

"We're seeing the development of digital media," he said. "It's 40%, or close to it, of our business, whereas 15 years ago it was virtually nothing."

Comcast reportedly was considering an investment in Vice, of which WPP owns about 10%. WPP also has invested in the website Refinery29, and in Media Rights Capital, which produces Netflix's  (NFLX - Get Report) "House of Cards."

"There are alternative distribution channels, and media owners are looking at these changes," Sorrell said. "If you're running a legacy business, you have to make sure your legacy business becomes digital as fast as possible, your digital properties expand as rapidly as possible, and thirdly that you invest and experiment."

Sorrell noted that Vice recently launched a channel called Broadly with WPP's second largest client, Unilever  (UN).  But Sorrell pointed out that while some new media companies like Netflix are gaining traction, Netflix is still not profitable.

WPP has a portfolio of $76 billion that it invests on behalf of its clients in media, with its largest investment being about $3.5 billion in Google  (GOOG - Get Report).