Brazil’s largest cryptocurrency exchange kept deposits and withdrawals suspended on Monday following a security incident affecting one of its systems. The shutdown temporarily barred customers from moving funds into or out of the platform while teams worked to bring operations back online.
In a statement published on X, Mercado Bitcoin reported that it had successfully identified and contained the breach. The firm assured customers that no data was leaked and that users would experience no financial losses, characterizing the freeze as a precautionary measure. According to Bloomberg, the company stated it plans to absorb the entire loss. Investigation teams are currently tracking assets, looking into the breach, and collaborating with local authorities.
The exchange has not yet disclosed which system was compromised, the total amount taken, or a specific timeline for reopening. Official updates have not provided a financial loss estimate or a reopening schedule.
Mercado Bitcoin has since released destination addresses associated with the unauthorized transactions, spanning Bitcoin, Solana, Stellar, Tron, and Ethereum-compatible networks. The company stated these addresses were shared to aid in tracking and identification. Meanwhile, blockchain security firm Hypernative estimated that suspicious transfers across multiple blockchains total over $40 million, though the exchange has not officially verified this amount.
Additional analysts have pointed to even higher loss figures and indicated that asset sweeping remains ongoing.
Stablecoin issuer Tether also participated in the response. Paolo Ardoino, CEO of Tether, announced on X at 10:06 a.m. ET that the company had successfully frozen more than 4.5 million USDT connected to the event. Notably, Tether invested $20 million in Mercado Bitcoin last July, at which time the exchange reported serving 4.5 million users.
A rough week for Mercado and other exchanges
This security breach arrives just days after one of the biggest cryptocurrency thefts in modern history. On October 29, hackers accessed $6.3 billion in assets at Binance after compromising an engineer’s laptop, which granted them entry to internal withdrawal-processing systems.
Binance reported no signs that private keys had been compromised. By November 1, the platform had replaced 95% of the missing funds and started reopening withdrawals in phases.
Regarding investigations, the FBI linked the attack to North Korea, while the U.S. Secret Service joined forces with Circle to trace and freeze assets. Tether announced it had frozen roughly $1.57 billion in USDT, and Circle reported freezing more than $800 million in USDC alongside law enforcement partners.
Binance later revealed that attackers exploited vulnerabilities beyond the initial engineer laptop compromise. The exchange has yet to release a comprehensive post-mortem detailing how the bad actors planned and carried out the exploit, which analysts estimate required at least 36 hours of preparation.
Additionally, the whereabouts of approximately $3.3 billion in unfrozen stolen funds remain unaccounted for, and Binance has not clarified how much it hopes to recover from that portion. Authorities continue tracking wallet movements across ten different blockchains.
Frequently Asked Questions
Are customer deposits safe at Mercado Bitcoin?
Mercado Bitcoin stated that customers suffered no losses and that the exchange intends to absorb all losses resulting from the incident.
Have withdrawals and deposits resumed?
Deposits and withdrawals were suspended on Monday following the security incident, and the company has not yet announced a reopening timetable.
How much money was lost in the incident?
Mercado Bitcoin has not provided an official loss total, but blockchain security firm Hypernative estimated suspicious transfers to be above $40 million.
What action has Tether taken?
Tether CEO Paolo Ardoino announced that the company froze more than 4.5 million USDT linked to the security breach.
