Both are leaving due to differences of opinion with majority shareholder GfK Verein, the company said late on Thursday, less than a week after issuing its second profit warning in a year.

GfK, known for its consumer confidence indices and TV audience ratings, said CEO Matthias Hartmann would hand over his duties to the management board before departing at the end of the year. Chairman Arno Mahlert will leave at the end of September.

GfK Verein is a non-profit think tank founded in 1934 in response to Germany's economic crises of the 1920s.

Its membership consists of hundreds of companies and a few individuals who receive basic annual statistics on the German economy in exchange for a small fee.

"New digital offers continue to place the conventional, personnel-intensive offers of ad hoc research under pressure," Hartmann wrote in a letter to shareholders published on Friday, referring to GfK's core custom-research business.

"GfK's performance in the second quarter of 2016 was well below our expectations."

GfK warned last week that it would underperform the wider market this year and its profitability would decline. Its shares plunged 19 percent last Friday in their worst single-day performance in more than a decade.

(Reporting by Georgina Prodhan; editing by Jason Neely)