Tether freezes $4.5 million as Mercado Bitcoin hacker holds $46 million in crypto

Tether CEO Paolo Ardoino confirmed the freeze on Nov. 2, saying the stablecoin issuer blocked more than 4.5 million USDT linked to the incident. Notably, Tether is a major investor in the exchange, having announced a $20 million strategic investment in Mercado Bitcoin in July to support its expansion into tokenization and other digital financial services.

Hackers Hold Millions

On-chain analyst Specter reported that coordinated efforts had expanded the immobilized assets to more than $9 million across nine digital assets, including USDC, PAXG, and RLUSD. Meanwhile, blockchain analytics firm Arkham Intelligence identified approximately $46 million in cryptocurrency held by wallets attributed to the attacker.

Exchange Response

Earlier today, Mercado Bitcoin disclosed that it had identified and contained a security incident affecting one of its systems overnight. The exchange temporarily suspended deposits and withdrawals while investigating suspicious asset movements but maintained that customers suffered no financial losses and that no personal information was compromised.

The exchange has not disclosed the financial extent of the attack or explained whether its corporate reserves were affected. Mercado Bitcoin subsequently published suspicious destination addresses across multiple networks to support tracing and potential recovery efforts.

Growing Security Concerns

The Mercado Bitcoin breach comes less than four days after hackers stole a record $6.3 billion from Binance on Oct. 29, extending a series of major attacks against centralized crypto exchanges. Binance's incident followed a $388 million security breach at Bitget on Sept. 24.

The attacks have revived concerns about the security of centralized trading platforms, which collectively custody billions in digital assets. Similar patterns emerged in 2025, with Bybit losing approximately $1.5 billion and Phemex suffering a $69 million breach.