That's almost a fifth of the US$44 billion (AU$63.6 billion) Elon Musk paid for it in 2022.

The valuation comes from investment asset manager Fidelity, which sank more than $US$19.66 million (AU$28 million) into the platform.

The valuation now puts the value of its stake at just over US$4.19 million (AU$6 million).

Recent research from data firm Kantar found that 26 per cent of advertisers plan on cutting their spending on X in the next year.

"Marketers are brand custodians and need to trust the platforms they use," The Guardian quoted Kantar director of global thought leadership Gonca Bubani in a statement last month.

"X has changed so much in recent years and can be unpredictable from one day to the next.

"It is difficult to feel confident about your brand safety in that environment."