London-based cryptocurrency exchange Exmo suffered a distributed denial-of-service attack on Monday, causing the platform’s servers to become unavailable.

In a tweet on Monday, Exmo reported that hackers had targeted the exchange with $75 million in trading volume in a distributed denial-of-service, or DDoS, attack. These cyberattacks typically overload a system with numerous requests from multiple virus-infected servers.

The attack comes two months after the crypto exchange reported that hackers had stolen $10.5 million in Bitcoin (BTC), Ether (ETH), XRP, Bitcoin Cash (BCH), Tether (USDT) and Zcash (ZEC). Executives later suggested some of the funds could not be recovered because the attackers had withdrawn $1 million in XRP and $2.8 million in ZEC through Poloniex.

According to data from CoinMarketCap, the total volume on Exmo has fallen 4.9% in the last 24 hours. The incident in December 2020 caused the exchange to lose about 5% of its total assets, though only Exmo’s hot wallets were reportedly affected by the hack.

Maria Stankevich, chief business development officer of Exmo, told Cointelegraph that since the December 2020 breach, the exchange has implemented a number of measures to reduce the possibility of a future attack. She said Exmo transferred cryptocurrency withdrawals to the custody arm of hardware wallet manufacturer Ledger and created a bug bounty program to test the exchange, among other solutions.

As of Jan. 10, all crypto exchanges in the United Kingdom are required to be registered with the country’s Financial Conduct Authority, which verifies they are in compliance with Anti-Money Laundering regulations. However, a number of firms that have submitted applications, including Exmo, have received temporary registrations from the FCA allowing them to continue trading until July 9.