- Twitter estimated in a filing earlier this month that fewer than 5% of its monetizable daily active users during the first quarter were fake or spam accounts.
- But Musk estimates that around 20% of the accounts on Twitter are fake or spam accounts and he's concerned that the number could be even higher.
- "My offer was based on Twitter's SEC filings being accurate," Musk tweeted early Tuesday morning.
Twitter estimated in a filing earlier this month that fewer than 5% of its monetizable daily active users — known as mDAUs — during the first quarter were fake or spam accounts.
But Musk estimates that around 20% of the accounts on Twitter are fake or spam accounts and he's concerned that the number could be even higher.
"My offer was based on Twitter's SEC filings being accurate," Musk tweeted early Tuesday morning. "Yesterday, Twitter's CEO publicly refused to show proof of <5%. This deal cannot move forward until he does."
Musk claims many of the spam accounts are "bots" but Twitter does not mention the word once in its SEC filing. Fake or spam accounts, often called bot accounts, are automated and not run by humans. But it's worth noting that automated Twitter bots, which are programmed to tweet set things at set times, can be good or bad and Twitter doesn't ban them all from the platform.
The company's shares slipped 2.46% in premarket trading Tuesday. A spokesperson for Twitter did not immediately respond to a CNBC request for comment.
Musk's tweet comes just a few hours after Parag Agrawal, Twitter's CEO, posted a lengthy thread about spam on the social network.
Agrawal, a software engineer, said that Twitter's spam estimates are based on multiple human reviews of thousands of accounts that are repeatedly sampled at random over time.
He said it's not possible for external groups to calculate the exact number of spam accounts on the platform because it requires both public and private information that Twitter can't share.
"Externally, it's not even possible to know which accounts are counted as mDAUs on any given day," he said.
Analysts at Jefferies said Tuesday that Musk looks to be trying to drive down the price due to the recent market sell-off.
"Elon Musk's recent comments suggest he is trying to negotiate a lower offer price," equity analyst Brent Thill and equity associate James Heaney said in a research note.
"We believe that Musk is using his investigation into the % of fake TWTR accounts as an excuse to pay below $54.20/share. In reality, the NASDAQ COMP is down 25% YTD [year-to-date] and Elon Musk realizes that he may be overpaying for the asset."
Musk has said his team is conducting its own analysis on the number of fake accounts on the platform, but experts in social media, disinformation and statistical analysis say his suggested approach to further analysis is woefully deficient.
"To find out, my team will do a random sample of 100 followers of @twitter," Musk tweeted Friday. "I invite others to repeat the same process and see what they discover."
He clarified his methodology in subsequent tweets, adding, "Pick any account with a lot of followers," and "Ignore first 1000 followers, then pick every 10th. I'm open to better ideas."
Musk also said, without providing evidence, that he picked 100 as the sample size number for his study because that's the number Twitter uses to calculate the numbers in its earnings reports.
"Any sensible random sampling process is fine. If many people independently get similar results for % of fake/spam/duplicate accounts, that will be telling. I picked 100 as the sample size number, because that is what Twitter uses to calculate <5% fake/spam/duplicate."
Carl T. Bergstrom, a University of Washington professor who co-wrote a book to help people understand data and avoid being taken in by false claims online, told CNBC that sampling 100 followers of any single Twitter account should not serve as "due diligence" for making a $44 billion acquisition.
He said that a sample size of 100 is far smaller than the norm for social media researchers studying similar issues and could result in selection bias.
Facebook co-founder Dustin Moskovitz weighed in on the issue via his own Twitter account, pointing out that Musk's approach is not actually random, uses too small a sample and leaves room for massive errors.
— Additional reporting by CNBC's Lora Kolodny.
Correction: This story has been updated to accurately describe how Twitter categorized the fake accounts in its SEC filing.