The SEC asked Twitter to explain its user metrics after Elon Musk complained

Illustration by Alex Castro / The Verge

In response to concerns of bot activity, the SEC conducted an active review of the number of users on the micro-messaging service. Federal regulators took Musk's allegations seriously after he raised concerns over the same users figures.

The review deals with many of the same concerns that Peiter Zatko reported to the SEC.

In a letter dated June 15th, the commission noted that the average number of false or fake accounts during the next fiscal year will be less than 5% of the total. Please tell us the methodology used in calculating these figures and the underlying assumptions used by management.

The methodology that is broadly consistent with the company's public statements was described by the company seven days later. According to the statement, a human review of thousands of randomly chosen accounts out of the mDAU sample is conducted each quarter.

This explanation was not good enough for the SEC. The company and its management are responsible for the accuracy and adequacy of their disclosures, notwithstanding any review, comments, action or omission of action by the staff, according to a new letter.

The mDAU system is at the center of both the short-lived takeover attempt by Musk and the recent whistle blower report. The smaller sample allows it to more effectively track whether real human users are seeing the ad space it sells. It's nearly impossible for outsiders to fact-check the company's numbers because they don't know if a given account is included in the mDAU sample.

The mDAU system was cited by Peiter "Mudge" Zatko in his report as a primary cause of growing bot activity on the platform.

A request for comment was not responded to by the company.