Brazilian trading platform Mercado Bitcoin hacked for over $40 million, deposits and withdrawals suspended.

November 2: Brazilian crypto trading platform Mercado Bitcoin suspended deposits and withdrawals on Monday local time after wallets associated with it were drained across at least 10 blockchains, with multiple security firms estimating losses exceeding $40 million.

Monitoring shared by Pablo Sabbatella, founder of crypto security firm Opsek, shows the largest outflow occurred around UTC 06:19–06:53, involving chains including Ethereum, Solana, Tron, Polygon, Arbitrum, Avalanche, BSC, and Stellar; attacker accounts now hold approximately 2,852 ETH, 106 BTC, 10,700 SOL, 6.7 million XLM, 77,000 AVAX, and more than 200 other tokens. The transfers were ordinary transactions, not smart contract exploits, and how signing permissions were obtained remains unclear.

Mercado Bitcoin said in a statement on X that it had "identified and quickly contained" the security incident, that customers were not harmed and there was no data breach, that the deposit and withdrawal suspension was a precautionary measure, and that it is tracking assets and cooperating with authorities. The platform subsequently published target addresses on chains including EVM, Bitcoin, Solana, Stellar, and Tron to facilitate tracking.

Tether founder Paolo Ardoino confirmed that approximately $4.5 million in USDT related to the incident has been frozen. There is currently no public evidence linking the incident to the recent Binance theft.