What you need to know in advertising today

Sir Martin Sorrell is not keeping a low profile. Or his opinions to himself.

The WPP founder and former CEO, who recently resigned from the ad agency holding companyamidst a cloud of allegations of misconduct, made a surprise appearance at the Digital Marketing Summit in New York on Tuesday.

During a keynote interview with Luma Partners CEO Terry Kawaja, the 73-year-old Sorrell joked about his current employment situation (or lack thereof) and declined to comment on what led to his ouster. But otherwise, he was candid about the ad industry and did not seem like a man ready to fade into retirement.

For a deeper look into his comments, click here.

In other news:

Facebook banned 583 million fake accounts in the first three months of 2018, the social network has revealed. It's a major effort towards transparency in the wake of the Cambridge Analytica scandal.

The US Justice Department and the FBI are reportedly investigating Cambridge Analytica, focusing on the company's financial dealings and how it acquired and used personal data pulled from Facebook and other sources. Prosecutors have sought to question former Cambridge Analytica employees and banks that handled its business.

Facebook is throwing more money at the problem of moderating content on its platform, with the bill spiralling into the millions of dollars, according to the Wall Street Journal. Most of the money is being spent on hiring more human moderators.

Amazon is opening its virtual reality and augmented reality toolkit to developers.Amazon Sumerian lets people build "mixed reality" apps without the need for dedicated programming or graphics skills.

Twitter will make users' tweets less visible if they generally misbehave on the platform. The company will use thousands of filters to determine how high their tweets appear in people's timelines.