Meta CEO Mark Zuckerberg lost nearly $9 billion from his estimated wealth in one day after Meta shares fell sharply.

Zuckerberg’s fortune dropped by about $8.9 billion to $257.5 billion on Friday, according to Forbes data cited by Yahoo Finance.

Meta shares fell around 4 percent during the session. The drop came just a day after the stock had jumped 4.5 percent.

Despite Friday’s decline, Meta shares had gained about 36 percent during September before the latest fall.

The decline came as investors continued to watch the huge amount that Meta and other technology companies are spending on artificial intelligence.

Goldman Sachs has raised concerns about the large AI investments being made by major tech companies and the amount of revenue they will need to generate to make those investments profitable.

Meta has been spending heavily on AI and has also been promoting its Muse AI assistant.

The fall in Meta shares directly affected Zuckerberg’s estimated wealth because he owns a large stake in the company.