Mercado Bitcoin confirms an incident
Mercado Bitcoin, Brazil's largest crypto exchange, says it identified and quickly contained a security incident in one of its systems early on November 2. The exchange says customers did not incur losses and no customer data was leaked.
It temporarily suspended deposits and withdrawals as a precaution while its teams investigate, trace the affected assets and coordinate with authorities. Mercado Bitcoin has not published a technical cause, a complete address list or an official loss figure.
Blockchain security firm Hypernative separately estimated that more than $40 million in suspicious transfers moved across at least ten networks, including Bitcoin, Ethereum, Solana and Tron. That figure is an external preliminary estimate, not a loss confirmed by Mercado Bitcoin.
The distinction matters: the exchange has confirmed a security incident and an operational pause, but the public evidence does not yet establish that customers lost $40 million or that every flagged transfer was unrecoverable.
A separate $106 million case remains an allegation
On the same day, on-chain investigator ZachXBT flagged an unrelated case involving an unnamed entity in the European Union. He alleges that more than $106 million was withdrawn as USDC and USDT from accounts held at several centralized exchanges on November 1.
ZachXBT says the suspected actor swapped USDC into ETH, routed assets through instant-exchange services including WellWallet and Kyrrex, used Wagyu to convert some funds toward Monero and bridged assets across several chains. He published eleven Ethereum-format addresses for compliance teams to monitor.
This second case is not a confirmed breach of a named exchange. The alleged victim and the exchanges have not been identified, the access method remains unknown and no affected company has publicly reconciled the $106 million estimate. ZachXBT also assessed with high confidence that the activity was not conducted by North Korea's Lazarus Group, but that attribution judgment is based on laundering indicators he has not fully disclosed.
Two alerts, two different confidence levels
The Mercado Bitcoin incident is company-confirmed, while the $40 million scale remains an outside estimate. The EU case is an investigator's attributed on-chain finding without confirmation from the unnamed victim.
Neither should be merged with the October 29 Binance breach. They involve different entities, different address clusters and, based on the currently published evidence, no demonstrated common attacker.
The clearest conclusion is therefore: Mercado Bitcoin has confirmed and contained a security incident and paused transfers, but has not confirmed Hypernative's reported $40 million figure. Separately, ZachXBT alleges an unnamed EU entity lost more than $106 million through compromised exchange accounts; that claim remains unconfirmed by the victim or the exchanges.
This is a developing story. Signal21 will update the coverage if Mercado Bitcoin publishes a post-mortem or the parties in the EU case identify themselves and reconcile the losses.
This publication is market analysis, not a recommendation to buy or sell.