Musk, CEO of automaker Tesla, is the world’s richest man, according to the Bloomberg Billionaires Index. He’s also one of the biggest personalities on Twitter and has regularly stirred controversy on the platform.

The billionaire could face scrutiny from US regulators by disclosing his massive stake days later than regulations allow, and because he revealed it in a filing typically reserved for passive investments. Ascending to Twitter’s board so swiftly after the disclosure could have complicated that process.

Musk is already seeking to exit a 2018 deal with the SEC that put controls in place related to his previous tweeting about Tesla.

Citing internal company messages, the Washington Post on Thursday reported that some workers in recent days have expressed concern on Twitter’s employee Slack channels that Musk could inflict damage to the company’s culture, as well as make it harder for people to do their jobs.

“Let’s tune out the noise, and stay focused on the work and what we’re building,” Agrawal said in his Sunday memo to employees.