Mining Pool Distribution

What this measures

This chart ranks mining pools by their share of blocks found over the last 12 months, according to mempool.space. A pool combines the power of many miners to smooth out their income: instead of waiting to find a block alone, which could take a small operator years, each one gets a steady payout in proportion to the work contributed. Only the top 15 pools are shown, so the shares do not necessarily add up to 100%.

An attribution, not a registry

No pool officially declares the blocks it has mined. mempool.space attributes each block by reading the tag pools write into the coinbase transaction, the one that pays out the reward, and by recognizing their known payout addresses. The method works well for the big names but remains imperfect: a pool can change its tag or leave it out, and unidentified blocks are grouped under “Unknown”.

More importantly, a tag says nothing about the actual infrastructure. Researcher 0xB10C compared the block templates that several pools send to their miners: some of them, listed as separate pools, appeared to simply relay AntPool’s. Because they keep their own tags, that grouping stays invisible on the chain. The 12-month window also smooths out recent moves: a shift of hashpower lasting a few weeks will only partly show up.

Coordinators, not owners

A pool does not own the power it displays. The machines belong to operators who can switch pools within minutes. In 2014, when GHash.io approached half of the network’s hashrate, some miners left it.

The real power of pools lies elsewhere: they build the block template, the list of transactions miners will hash. With the Stratum protocol, still used by most pools, the miner receives this work without being able to change it. A pool that decides to exclude certain transactions, under regulatory pressure for example, does so for all the power it coordinates. In 2021, Marathon’s pool briefly produced blocks filtered against US sanctions lists (OFAC) before reversing course.

🪙 What is a Drivechain, and why does it divide the Bitcoin community so much?

Stratum V2 offers a different split of roles. It lets miners choose the transactions in their own blocks, with the pool simply pooling risk and distributing rewards. Its deployment remains limited for now.

The real sensitivity is not whether a pool will one day cross 50%. It is that the choice of transactions remains concentrated in the hands of a few companies, and therefore of the jurisdictions they operate in.