Martin Sorrell, the founder of the world's largest advertising and PR group, WPP, said the Facebook advertising boycott has not had a major impact.
Advertisers announced various degrees of pauses to their social media advertising budgets in June, after a campaign called "#StopHateForProfit" called on them to boycott Facebook for the month of July. Some companies said they'd only pause ads on Facebook for July. Others said they'd do it through the end of the year.
More than 1,000 groups and companies took part in the boycott, hoping to pressure Facebook into taking more stringent steps to stop the spread of hate speech and misinformation on its platform. Participants included the likes of HP, Verizon, Coca-Cola, Diageo, and Ben & Jerry's.
"We haven't seen that much of a slow down on Facebook," Sorrell told CNBC's "Squawk Box Europe" on Wednesday. "Obviously the so-called boycott had a little impact, but much less than people forecast."
The British businessman said the boycott "wasn't the right way to deal with Facebook."
Sorrell, whose companies profit when brands spend on advertising, said brands should have told Facebook what their concerns were in private.
"You don't confront them in public," he said. "What you do is try and lobby privately for changes and I think they've made changes. They have 35,000 people monitoring editorial content. They take down some of the extreme groups, they've altered the nature of the algorithm."
Stop Hate For Profit has previously described the success of its campaign as "unmistakable," saying it "forced an unprecedented public examination of Facebook's deep harms to marginalized communities and the health of our democracy."
On August 11, the campaign group published a review on Facebook's progress to their recommendations. It concluded the social media giant had fallen short on attempting to address four key issues and failed to take any meaningful action on four other areas.
Facebook conceded in late July that the boycotts had impacted second-quarter earnings, but anticipated ad revenue would continue to grow in the third quarter.
Sorrell is also the founder and executive chairman of advertising firm S4Capital, which announced Wednesday that it has turned a profit for the first time, despite the coronavirus pandemic. Gross profit came in at £124 million ($160 million) and revenue came in at £141.3 million.
— CNBC's Megan Graham contributed to this article.