Mercado Bitcoin suspends deposits and withdrawals after an estimated $40M+ drained from its wallets across 10+ chains

Summary

Brazilian exchange Mercado Bitcoin said on 2 November 2026 that it had identified and swiftly contained a security incident in one of its systems overnight, and temporarily suspended deposits and withdrawals as a precaution. Security firms cited by CoinDesk estimate more than $40 million was moved out of exchange-associated wallets across at least 10 blockchains; the exchange has not confirmed an amount. Mercado Bitcoin later published the destination addresses identified in the incident-related transfers.

Affected

• Mercado Bitcoin (centralized exchange) hot/exchange-associated wallets on Ethereum and other EVM chains, Bitcoin, Solana, Tron, Stellar and others
• No fix applicable; the exchange states the incident was contained

Impact

According to CoinDesk, the largest outflows occurred between 06:19 and 06:53 UTC and were plain transfers rather than a smart-contract exploit; how the attacker obtained signing access is not known. Mercado Bitcoin states customers suffered no losses and no data was leaked. Tether CEO Paolo Ardoino stated Tether froze more than 4.5M USDT related to the incident. No attribution has been published.

Recommended actions

• Exchanges, bridges, OTC desks and stablecoin issuers: screen and flag deposits from the destination addresses listed in the indicators below.
• Mercado Bitcoin customers: follow only the exchange's official channels for the resumption of deposits and withdrawals, and beware of phishing that exploits the incident.
• Note: the Stellar address in Mercado Bitcoin's post (GDXYRI6IONQA5YTGRLQ603FGJ2BWXPJTTQPUXFPSEXSRKBZLFKMZSOLP) contains a character that is invalid in a Stellar address and is therefore not included as an indicator.

Source & attribution

This 0xCERT advisory summarises statements by Mercado Bitcoin (https://x.com/MercadoBitcoin/status/2117239507263132056 and https://x.com/MercadoBitcoin/status/2117261565200146525), reporting by CoinDesk (https://www.coindesk.com/business/2026/11/02/brazil-s-mercado-bitcoin-halts-withdrawals-after-usd40-million-drained-across-10-chains) and Tether's Paolo Ardoino (https://x.com/paoloardoino/status/2117272224814219720). Indicators are copied verbatim from Mercado Bitcoin's post. Details may change; refer to the original sources for the authoritative record.