Mercado Bitcoin Hacked: $40M in Suspicious Outflows Flagged

Brazil’s biggest cryptocurrency exchange, Mercado Bitcoin (MB), was reported hacked by several blockchain monitors. MB acknowledged the breach and temporarily halted deposits and withdrawals.

Blockchain security company Hypernative placed potential losses from MB wallets at $40 million. The event occurred just days after the record $6 billion Binance hack.

BRAZIL'S LARGEST EXCHANGE CONFIRMS BREACH AS $40M SUSPICIOUS OUTFLOWS EMERGE

Mercado Bitcoin temporarily suspended deposits and withdrawals after detecting and containing an internal security incident. @HypernativeLabs flagged more than $40 million in suspicious outflows…

— BeInCrypto (@beincrypto) November 2, 2026

The exchange published a full statement, translated from Portuguese:

We identified and quickly contained a security incident in one of our systems overnight.

We stress that:
• There was no loss to clients;
• There was no data leak.

As a preventive protection measure, deposits and withdrawals are temporarily suspended. Our teams are mobilized investigating the case, tracing the assets and coordinating measures with the competent authorities.

We will keep providing regular updates here.

The announcement did not include a date for the return of deposit and withdrawal services.

Hypernative’s Findings

Hypernative said the suspected attack touched wallets on at least ten different blockchains, including Bitcoin, Ethereum, Solana, Tron, Polygon, Arbitrum, Avalanche, BNB Smart Chain, and Stellar.

The earliest unusual activity appeared around 11 PM Sunday local time in Brazil.

Most assets from MB-linked wallets were sent to recently created addresses tied to the possible attacker.

MB’s statement mentions a breach 'overnight,' the same period as those transfers, but does not directly link them.

The transfers were standard cryptocurrency moves, not smart-contract exploits, and they bore signatures making them appear authorized by the source wallets.

Hypernative said it is still uncertain how the unauthorized signings were possible. Remaining questions include whether private keys were exposed or if the transfer approval system had weaknesses.

Unanswered Questions

It remains unclear how the incident began, the exact sum taken, whether affected assets were client funds or exchange holdings, and when services will resume.

MB said it is investigating, tracking the cryptocurrency movement, cooperating with authorities, and will provide regular updates.

The story is still unfolding.