Crypto giant Binance signed a nonbinding agreement on Tuesday to buy FTX's non-U.S. unit to help cover a "liquidity crunch" at the rival exchange, in a stunning bailout that raised fresh concerns among investors about cryptocurrencies, Reuters reports. 

The deal between high-profile rivals Sam Bankman-Fried, FTX's CEO, and Binance CEO Changpeng Zhao came as speculation about FTX's financial health snowballed into $6 billion of withdrawals in the 72 hours before Tuesday morning.

The pressure on FTX came in part from Zhao, who had tweeted on Sunday that Binance would liquidate its holdings of the rival's token due to unspecified "recent revelations."

The move, a dramatic reversal in fortunes of billionaire Bankman-Fried, 30, is the latest emergency rescue in the world of cryptocurrencies this year, as investors pulled out from riskier assets amid rising interest rates. The cryptocurrency market has fallen by about two-thirds from its peak to $1.07 trillion.