Lubian suffers in silence, Arkham reveals gaping holes in crypto oversight

A previously unreported Bitcoin theft from late 2020 has now been revealed as the largest crypto hack in history.

According to a new analysis by blockchain intelligence firm Arkham, 127,000 BTC—worth $3.5 billion at the time—was drained from the Chinese mining pool Lubian on Dec. 28, 2020. The breach went unnoticed for more than four years and eclipses the recent $1.5 billion Bybit breach .

Lubian, once a top-10 Bitcoin mining pool that controlled nearly 6% of the global hash rate, abruptly shut down in early 2021. At the time, the crypto community attributed the exit to tightening regulations in China and Iran, where many of Lubian’s mining machines were believed to operate.

Arkham’s findings now point to a devastating security failure as the real cause. The firm believes the hack stemmed from weak private key generation methods.

Lubian has muted meltdown

Despite losing nearly all of its Bitcoin holdings, Lubian never disclosed the incident, nor did the hacker ever publicize the theft. In a desperate recovery effort, Lubian issued over 1,500 small Bitcoin transactions containing pleas for the return of the stolen assets. The pool also moved its remaining 11,880 BTC into designated recovery wallets.

The hacker has not attempted to cash out the stolen coins, which remain idle apart from a 2024 consolidation into a new wallet address. Arkham’s report raises fresh concerns over transparency and operational security among major crypto infrastructure players—especially as billions in assets flow through centralized entities with limited oversight.

The discovery retroactively redefines the scale of crypto’s largest known heists and casts Lubian’s 2020 disappearance in a new, more troubling light. Investigations into the identity of the attacker and the precise vector of the exploit are ongoing.