Circle and Tether on Thursday froze over $2.38 billion in stablecoin currency after Binance said it was actively investigating a potential security issue.

Binance, the world’s largest cryptocurrency exchange, said in a post on X its teams were reviewing all relevant information with urgency and added that user funds were safe.

Crypto firm Ripple had frozen roughly $200 million, Binance co-founder Yi He said on X.

Binance co-founder Changpeng Zhao, who no longer manages the company, wrote on X that the incident “looked like a hack.”

Tether, which issues the world’s…