Turkish cryptocurrency exchange BtcTurk has frozen deposits and withdrawals after about $48 million to $50 million in digital tokens were siphoned from its wallets in a suspected hack, according to blockchain-security firms Cyvers and CertiK. On-chain data show large holdings of Ether, Avalanche, Arbitrum, Base, Optimism, Mantle and Polygon tokens moved to two newly created addresses before being rapidly converted into ether, a pattern analysts say is consistent with an exploit rather than routine transfers. Some investigators believe a compromised private key may have allowed the attacker to authorise the withdrawals. Founded in 2013 and regarded as Turkey’s oldest and second-largest crypto exchange, BtcTurk said it is working with external investigators and law-enforcement authorities while it assesses the scale of the breach. The incident underscores the continuing vulnerability of centralised trading venues to multi-chain attacks.