Brazil's Mercado Bitcoin pauses deposits and withdrawals after security incident; security firms estimate more than $40 million moved

Mercado Bitcoin, a crypto exchange based in Brazil, suspended deposits and withdrawals on Monday 2 November after what it called a “security incident” in its systems early that morning, the company said in a statement on X, CNN Brasil reported.

What the exchange said. Mercado Bitcoin said it had “identified and swiftly contained” the incident, that it caused no losses to customers and that no data was leaked, according to CoinDesk and CNN Brasil. Deposits and withdrawals were paused as a precaution while its teams investigate, trace the assets and coordinate with authorities, the company said. It later published the destination addresses that received the funds, to help others track them. As of its latest statements, the exchange had not said how much was taken or how the incident happened.

What security firms said. Security firms estimated that more than $40 million was moved from wallets linked to the exchange on at least 10 blockchains, including Ethereum, Solana, Tron, Polygon, Avalanche and Stellar, CoinDesk reported. A report shared by Pablo Sabbatella, founder of security firm Opsek, said most of the outflows took place between 06:19 and 06:53 GMT. CoinDesk said the transfers were ordinary transactions, not a smart-contract exploit. These figures have not been confirmed by Mercado Bitcoin.

Frozen funds. Tether chief executive Paolo Ardoino said about $4.5 million in USDT stablecoins linked to the incident had been frozen, according to CoinDesk and CNN Brasil.

No one has been named as responsible, and there is no public evidence linking the incident to the record theft from Binance last week, CoinDesk reported. See also: the FBI’s attribution of the Binance theft.