Mercado Bitcoin halts deposits and withdrawals after a suspected $40 million hack

Mercado Bitcoin, one of Brazil's largest crypto exchanges, suspended deposits and withdrawals on Monday, November 2, after a security incident. Blockchain security firm Hypernative flagged more than $40 million in suspicious transfers that may be linked to the incident, Decrypt reported.

What happened

In a Portuguese-language statement on X, the exchange said it had identified and quickly contained a security incident in one of its systems early that morning, according to Decrypt's translation and Tecnoblog. It said no customer funds were lost, no customer data was exposed, and that its teams were tracing the assets and coordinating with the authorities.

Hypernative's figure of more than $40 million is a preliminary on-chain estimate covering transfers across at least 10 blockchains. Most of the transfers took place between 06:19 and 06:53 UTC, Tecnoblog reported, citing Hypernative. Reports of the exchange's own figure differ: Bitcoin.com News reported on November 3 that the incident involved about $38 million, while a Reuters-based report said a November 4 post by the exchange on X put the affected assets at $36.3 million, with $12.9 million blocked.

Tether CEO Paolo Ardoino said on X that the company froze more than 4.5 million USDT related to the incident, Decrypt reported.

The reopening plan

On November 4, Mercado Bitcoin told Cointelegraph that it would begin a phased reopening on Monday, November 9, starting with access to balances and statements; its help center gave the same date and, when we read it on November 9, said trading, withdrawals, deposits, and transfers were not yet possible. Transfers, withdrawals, and trading would follow later, subject to independent security testing. The exchange pledged to use company funds to replenish the affected assets and said more than $15 million in stolen funds had been frozen. Other reports of the frozen amount are lower.

Why it matters

The incident came four days after the record Binance theft, and it followed the same pattern on a smaller scale: an exchange system was breached, funds were moved out, withdrawals were halted, the exchange said customers would not lose money, and a stablecoin issuer froze part of the funds.

What it could mean for traders

Mercado Bitcoin's pledge to cover the loss depends on its own capital, so the size of the loss relative to the company matters more than the headline number. Traders with balances on the platform face access risk until withdrawals resume. The next markers are a confirmed loss figure, the pace of the phased reopening, and any technical explanation; see also how exchanges absorb hacks.