The current economic environment of low growth is the biggest problem for profit making, the chief executive officer of the world's largest advertising firm by revenues has told CNBC.
"The biggest issue is this low growth economy, where clients are not willing to invest in brand, or more importantly in innovation," Martin Sorrell, the CEO of WPP, told CNBC on Monday.
"There isn't enough investment in brand," Sorrell added, saying that this is what keeps him awake at night.
Sorrell recognized that political uncertainty is a concern, but he hasn't seen his business hurt on the back of the U.S. election campaign.
"Of course (political uncertainty) matters … Although I have to say we haven't seen what some of our competitors have been talking about, an impact of the U.S. presidential election on (the third quarter) in North America which continues to be quite strong," Sorrell told CNBC.
WPP reported Monday higher revenues during the third quarter of this year compared to the previous three-month period. However, growth seems to be slowing at the firm, with a rise of 3.2 percent in like-for-like revenues, down from 4.3 percent for the first half of this year. Shares were up 3 percent by mid-morning in the European trading session on Monday.
When asked about the AT&T-Time Warner deal, Sorrell said it should bring more choice for consumers while making advertising opportunities more competitive.