Mercado Bitcoin Suspends Withdrawals After Suspicious Transfers

Brazilian crypto exchange Mercado Bitcoin suspended deposits and withdrawals following suspicious transfers across at least 10 blockchain networks. Security researchers estimate that more than $40 million in digital assets moved to unfamiliar wallets.

Tether froze approximately $4.5 million in USDT connected to the incident. The exchange says the situation has been contained, but the attacker’s identity and method of access remain unknown.

Mercado Bitcoin Halts Withdrawals Following $40M Security Incident

Brazilian cryptocurrency exchange Mercado Bitcoin has suspended deposits and withdrawals after suspicious wallet activity reportedly resulted in more than $40 million worth of digital assets being transferred to new addresses.

The incident affected wallets across at least 10 blockchain networks, including Ethereum, Bitcoin, Solana, Tron, Polygon, Arbitrum, Avalanche, BNB Chain, and Stellar.

According to blockchain security researchers, the largest wave of transfers occurred within approximately 34 minutes on Monday, between 06:19 and 06:53 UTC. The reported movements included around 2,852 ETH, 106 BTC, 10,700 SOL, 6.7 million XLM, and 77,000 AVAX, alongside hundreds of other tokens.

However, Mercado Bitcoin has not independently confirmed the estimated $40 million loss, leaving the full financial impact uncertain.

Exchange Assures Users as Investigation Continues

In a statement published on X, Mercado Bitcoin said it had identified and contained the security incident. The exchange also stated that customers had not been harmed and that no data breach had occurred.

Deposits and withdrawals remain suspended while the company investigates the transactions, tracks the movement of funds, and works with the relevant authorities.

The platform has reportedly shared destination wallet addresses across multiple networks to help blockchain investigators and other industry participants monitor the assets.

One of the biggest unanswered questions is how the suspicious transactions were authorized. So far, investigators have not publicly established whether the incident involved compromised credentials, access to private keys, or another security weakness. There is also no confirmed evidence that a smart contract vulnerability caused the transfers.

Tether Freezes $4.5 Million in USDT

Tether founder Paolo Ardoino confirmed that approximately $4.5 million in USDT associated with the incident had been frozen. The intervention could help prevent the affected stablecoins from being moved or converted, although the recovery of the remaining assets has not been confirmed.

The incident adds to growing concerns about cryptocurrency exchange security, particularly for platforms managing assets across multiple blockchain networks.

It also follows a separate security incident involving Binance, with the FBI attributing a reported $6.3 billion loss to North Korea’s TraderTraitor hacking group. No public evidence currently links the two incidents.

For Mercado Bitcoin, the immediate priorities are determining the full extent of the transfers, identifying how the wallets were accessed, and restoring normal services safely. Until further details emerge, the incident serves as another reminder of the security challenges facing centralized cryptocurrency exchanges.