Cryptocurrency exchange BitMart was hit by a large-scale hack that resulted in thousands of assets being stolen. The worth of the stolen assets is estimated to be $196 million.

BitMart first notified users of the breach on Dec. 4, providing an initial estimate of $150 million of assets stolen. The company suspended deposits and withdrawals temporarily and announced that a reinstatement timeline would become available later in the week.

"In response to this incident, BitMart has completed initial security checks and identified affected assets. This security breach was mainly caused by a stolen private key that had two of our hot wallets compromised. Other assets with BitMart are safe and unharmed." Bitmart wrote in a Dec. 6 update. "BitMart will use our own funding to cover the incident and compensate affected users. We are also talking to multiple project teams to confirm the most reasonable solutions such as token swaps. No user assets will be harmed."

The BitMart hack is the latest large-scale crypto-asset theft. Defi firm Poly Network revealed in August that it had been hacked, with $610 million in assets stolen. The hacker would later return the stolen assets but did not clearly explain why he had hacked Poly Network.

Unlike the Poly Network incident, the hackers that struck BitMart took care to cover their tracks.

Blockchain security and analytics firm Peckshield assisted BitMart in its investigation. Peckshield found that hackers had used the 1inch network to convert the stolen assets. The hackers then used the privacy program Tornado Mixer to hide the destinations of the tokens.

The BitMart hack may only be the latest to come. The increasing payouts of defi hacks and the relative ease of making a clean escape have made cryptocurrency theft far more lucrative to hackers.