Mercado Bitcoin goes offline after security incident drains over $45 million

What happened

Mercado Bitcoin, described by The Daily Hodl and ZyCrypto as Brazil's largest crypto exchange, has taken its platform offline following a security incident that moved tens of millions of dollars in digital assets. The company said it identified and contained the problem in one of its systems early in the day, and it suspended deposits and withdrawals while teams investigate and trace the funds.

According to The Daily Hodl, which cited Valor Econômico, the exchange says no clients lost money and no data leaked. Mercado Bitcoin also said roughly $11.2 million of the assets has already been blocked with assistance from Tether, Circle, BRL1, Paxos and Chainalysis. ZyCrypto reported a similar blocked figure of about $11 million, crediting the same group of crypto firms.

The exchange published the destination wallet addresses linked to the incident across EVM networks, Bitcoin, Solana, Stellar and Tron so that the wider community could help monitor the funds. Tether chief executive Paolo Ardoino said the stablecoin issuer had frozen more than 4.5 million USDT tied to the incident. Mercado Bitcoin said operations will stay suspended until it can restart safely, with a timeline to be shared on its official channels, and warned users about impersonation scams, stressing that it never asks for passwords, verification codes or recovery phrases.

Why it matters

The incident hits the country's biggest trading venue and has left customers unable to move funds on or off the platform, which puts operational resilience and custody arrangements under scrutiny. ZyCrypto noted that repeated breaches weigh on market sentiment regardless of which company ultimately absorbs the losses, and that policy watchers warn attacks on prominent platforms can dent broader confidence in digital assets. The wide spread in reported loss figures also illustrates how quickly early estimates shift while investigators trace transactions across multiple chains.

What the data shows

The numbers reported so far do not fully agree. The Daily Hodl framed the incident as involving about $49 million in crypto assets, while noting that blockchain data firm Arkham put the amount drained at roughly $46.3 million. Security firm Hypernative had earlier flagged about $40 million in outflows from wallets it attributes to the exchange.

ZyCrypto reported that initial research placed losses at $40 million before Arkham Intelligence analyst Emmett Gallic identified an additional $5 million, and that the platform itself valued the assets involved at $38 million. Gallic said the losses were still growing and that attackers were targeting old deposit addresses to sell off memecoins and altcoins, according to that report. Both outlets reported that a sum in the region of $11 million was blocked, and Ardoino's frozen USDT figure adds a further recoverable amount.

Background

Mercado Bitcoin is described in both reports as the largest exchange in Brazil, giving the incident significance beyond a single company's balance sheet. ZyCrypto placed the attack within a run of exchange breaches over roughly a 30-day span, noting that one earlier incident at Bybit drained close to $1.5 billion and that US intelligence agencies attributed that theft to North Korean hackers. The exchange said the method used in this incident remains unknown.

What is still unclear

It is not yet established how attackers gained access to the affected system, and Mercado Bitcoin has not given a timeline for restoring service. It is also unclear how much of the traced crypto can ultimately be recovered and returned, how the frozen stablecoin balances will be handled, and whether the final loss figure will settle nearer the exchange's $38 million estimate or the higher figures reported by analysts.

What to watch

The next signals will be the restart schedule published on Mercado Bitcoin's official channels, any update on the blocked and frozen assets, and whether Brazilian authorities comment on the investigation. Further blockchain tracing may also narrow the gap between the competing loss estimates.

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