Major Exchange Halts Transfers Amid Suspected $40M Breach

Brazil's largest cryptocurrency platform kept all client deposits and withdrawals suspended on Monday following a security incident within one of its systems. The operational shutdown left customers entirely unable to move funds into or out of the platform while technical teams worked toward restoring normal functionality. Representatives for Mercado Bitcoin stated on X that the breach has been identified and contained, describing the platform-wide suspension as a precautionary measure.

The exchange emphasized that no user data had leaked during the intrusion. Internal teams are currently investigating the matter, actively tracing the missing digital assets, and coordinating their response with relevant authorities. According to a Bloomberg report cited by the platform, the firm plans to absorb the financial impact entirely, maintaining that customers have not incurred any losses.

While the trading platform has not disclosed which specific system was breached, a timeline for reopening, or the total value of the compromised assets, blockchain security analysts have begun tracking the outflows. Hypernative, a blockchain security firm, issued preliminary estimates indicating that suspicious onchain transfers have exceeded $40 million. The exchange has not confirmed this financial figure. Other unnamed analysts suggest the final losses could be higher, noting that fund sweeping by the attackers is still ongoing. To assist with tracking efforts, Mercado Bitcoin released destination addresses linked to the unauthorized transfers across multiple networks, specifically covering Bitcoin, Solana, Stellar, Tron, and Ethereum-compatible blockchains.

Industry Partners Respond

Stablecoin issuer Tether quickly intervened to block a portion of the outgoing assets. At 10:06 a.m. ET, Tether Chief Executive Officer Paolo Ardoino announced on X that his organization successfully froze over 4.5 million USDT connected to the security breach. The stablecoin operator previously backed Mercado Bitcoin with a $20 million investment in July, a period when the Brazilian trading platform reported a user base of 4.5 million individuals.

String of Exchange Incidents

The system breach in Brazil occurred mere days after an unprecedented cyberattack on Binance on October 29. During that incident, malicious actors compromised a single engineer's laptop, ultimately gaining access to internal withdrawal processing systems and reaching $6.3 billion in digital assets. While Binance reported finding no evidence of exposed private keys, the exchange later identified additional breach points beyond the initial laptop compromise.

The platform has not released a comprehensive post-mortem detailing the attackers' methods, though preliminary estimates indicate the operation required a minimum of 36 hours of preparation. By November 1, Binance had begun a phased restoration of withdrawals and replaced 95 percent of the taken assets. However, an estimated $3.3 billion of the stolen funds remains unfrozen, with their final destination not yet entirely explained and recovery expectations unclear. Investigators are currently monitoring wallet movements across ten different blockchains.

Federal authorities have stepped in regarding the October breach. The FBI formally attributed the $6.3 billion attack to North Korea. The United States Secret Service is also collaborating with stablecoin issuer Circle to track and freeze the illicit flow of funds. In response to the Binance attack, Tether reported freezing approximately $1.57 billion in USDT, while Circle coordinated with authorities to freeze more than $800 million in USDC.