WPP Plc Chief Executive Officer Mark Read is set to retire at the end of the year, kicking off a search for a successor at one of the world’s largest advertising agency groups as it grapples with slowing sales. 

Read, 58, has helmed the British company for about seven years and has been with the company for more than 30 years, the company said in a statement on Monday.

WPP, once the largest ad agency globally, has been working on ways to reignite growth and streamline its operations to address softening sales and a gloomy outlook. The global economic downturn has hit client spending, especially in Asia, and the rise of artificial intelligence capabilities to automate ad creation and distribution is raising doubts across the ad industry.

In February, WPP shares dropped after the group forecast sales would remain flat or shrink this year, missing analysts’ estimates, while rival group Publicis Groupe SA said it expects organic growth of between 4% and 5% this year. 

The company had previously restructured its stable of brands to cut costs and announced a plan to spend hundreds of millions of pounds on new technologies, including building out AI capabilities. 

Read’s retirement highlights “the challenge his successor faces to overcome years of financial and share-price underperformance against rivals, and opens the prospect of strategic and structural shifts,” said Matthew Bloxham, senior industry analyst at Bloomberg Intelligence. “The new leader will need to double down on simplification, cost-cutting and technology investment.”

Former BT Group Plc head Philip Jansen was appointed chairman of the ad group in January.

This story was originally featured on Fortune.com