Elon Musk called up the chief executives of companies that pulled advertising spending from Twitter to complain, the Financial Times reported.
A number of leading media buyers and advertising agencies say that almost all the major brands they act for have stopped ad spending on Twitter, the report said.
Musk took it upon himself to personally call CEOs to chastise them, one industry figure told the FT, but his actions have backfired, the newspaper reported.
Half of Twitter's top 100 advertisers have stopped advertising on the platform in recent weeks as a result of "controversies" and "warnings from media buyers." The list includes Meta, Coca-Cola and Kellogg's, according to a report by Media Matters.
Four industry figures told the Financial Times that in recent weeks agencies have not little communication with Twitter's ads business team because so few staff were left following mass layoffs.
Twitter's ad systems have become bug-ridden, according to some media buyers, making it nearly impossible to launch campaigns.
"It is quite unique. The turmoil, the damage, nothing of this magnitude has happened before. Never," a big four advertising agency executive told the FT.
Derrick Johnson, the president of civil rights organization the NAACP, last week urged advertisers to stop using Twitter because of Musk's decision to reinstate former US president Donald Trump's account.
"Any advertiser still funding Twitter should immediately pause all advertising now," Johnson tweeted.
The NAACP chief also hit out at Musk's use of a "garbage poll" to determine if he should let Trump return.