Bitcoin pool mines seven blocks in a row, raises security concerns

Antpool, the second-largest Bitcoin (BTC) mining pool, mined seven blocks in a row on May 17, raising security concerns. The seven-block sequence confirmed 20,686 transactions, rendering over 23 BTC, worth around $1.54 million, in revenue.

In particular, the event happened between block heights 843,898 and 843,904 and lasted one hour and 38 minutes. According to mempool. space data, Antpool collected 1.283 BTC in fees, plus 21.875 BTC from the block subsidy.

Block heights 843,898 to 843,904. Source: mempool.space / Finbold

Interestingly, Foundry USA, the largest Bitcoin mining pool, mined the previous block of this sequence and the two next blocks. This makes a sequence of 10 blocks mined by two companies, challenging the decentralization and security of the leading cryptocurrency.

Bitcoin mining pools weekly ranking. Source: mempool.space / Finbold

In this context, a Bitcoin developer believes transactions should wait at least two hours before being considered secure. This is because the more subsequent blocks after the one carrying a transaction, the lower the chances of a chain reorg and the more probable a transaction is to reach finality.

Antpool’s recent seven-block sequence demonstrates that the developer’s concerns are real and should be considered.