Binance, the world's largest cryptocurrency exchange, paused withdrawals of the stablecoin USDC on Tuesday while it carried out a "token swap."
USDC withdrawals were resumed about 8 hours after Binance first announced the pausing of withdrawals.
The move came as investor concerns grow about Binance's stability following the collapse of rival exchange FTX as well as a report of a potential criminal investigation from the U.S. government.
Binance said earlier on Tuesday it had "temporarily paused" USDC withdrawals while it does a "token swap." This involves swapping one cryptocurrency for another without the need for fiat currency.
Changpeng Zhao, CEO of Binance, tweeted that the exchange is seeing an increase in withdrawals of USDC, a cryptocurrency known as a stablecoin because it is pegged one-to-one with the U.S. dollar.
USDC is used by investors to trade in and out of different cryptocurrencies without the need to move money back into U.S. dollars. If traders are withdrawing USDC from Binance, it could be to move it onto another platform.
Zhao said that any transfers into USDC from the stablecoin known as PAX, as well as Binance's own token BUSD, require routing through a bank based in New York which is not yet open. The suggestion from Zhao is that users are looking to convert their PAX and BUSD into USDC in order to withdraw their funds from Binance.
A token swap could be a way for Binance to get more USDC quickly while the banks are closed in order to resume withdrawals for customers.
Zhao said users could still withdraw other stablecoins including BUSD and tether. Deposits are not affected, he said.
Binance's own token called BNB was trading down about 5% on Tuesday morning, according to data from CoinGecko.
It's not normally good news when a crypto firm has to pause withdrawals. In the summer, crypto firms including lender Celsius had to pause withdrawals before ultimately filing for bankruptcy. There is no indication of any such trouble for Binance.
In the past 24 hours, Binance has seen $1.6 billion of outflows from its platform, according to a tweet from crypto data company Nansen published early Tuesday. Binance has more than $60 billion of assets on its platform, Nansen said.
Investors jittery
The collapse of FTX and arrest of its former CEO Sam Bankman-Fried has crypto investors on edge with fears of further contagion across the industry.
Binance has been in the spotlight since its decision to sell its stake in FTX's self-issued FTT digital tokens, which preceded the failure of the rival exchange.
Investors have called for more transparency from Binance's business. Last month, the company issued a proof of reserve in which it claims to have a reserve ratio of 101%. That means it has enough assets to cover customer deposits.
But critics have said that the proof of reserves have not gone far enough to give assurances of Binance's collateral. Mazars, the auditing firm Binance used for its proof of reserves, said in its five-page report that the company does "not express an opinion or an assurance conclusion."
Investors are also keeping tabs on a report from Reuters that U.S. Department of Justice prosecutors are delaying the conclusion of a criminal investigation into Binance. Reuters, citing four people familiar with the matter, reported that the investigation is focused on Binance's compliance with anti-money laundering laws. Binance responded saying: "Reuters has it wrong again."
"We don't have any insight into the inner workings of the US Justice Department, nor would it be appropriate for us to comment if we did," the company said in a tweet on Monday.