Sam Bankman-Fried is racing to raise as much as $8bn to save his crypto empire as more of his former backers write down their investments in the FTX exchange.

The 30-year-old conceded on Twitter on Thursday that the FTX trading venue has an insufficient store of readily accessible funds to meet client demands. Investors pitched by Bankman-Fried described a chaotic appeal from the humbled crypto chief executive to plug his company’s financial hole.

The outcome of Bankman-Fried’s dash for cash will determine the fate of FTX amid mounting doubt about its ability to remain afloat without an injection of fresh capital, and anxiety for customers with money stuck on the frozen exchange. In a sign of how pressures are rising across businesses affiliated with him, FTX US, which is separate from the international exchange, said it may halt trading on its platform in coming days.