The biggest decentralization move Bitcoin mining has seen in years has happened quietly, with seven of the largest pools agreeing to support the same open standard.
Foundry, AntPool, F2Pool, SpiderPool, MARA Pool, Block Inc and DMND have all joined the Stratum V2 working group, the group announced last week.
Stratum V2 is an open source protocol governing how mining pools communicate with individual miners in those pools. The biggest practical change it introduces is allowing individual miners to build their own block models, meaning that the choice of which transactions to include in each new block rests with the miner rather than whoever operates the pool.
Foundry alone controls 34.2% of the global Bitcoin hashrate, with AntPool 14.2%, F2Pool 11.3% and SpiderPool 10.5%, with MARA Pool adding 4.7%, according to Hash Index data. Together with the rest of the Stratum V2 signatories, the seven pools that now support the standard account for almost 75% of all Bitcoin hashrate.
Under the current Stratum V1 standard, transaction selection for almost every new block falls to the pool operators rather than the individual miners who actually do the work. This concentration represents the most significant structural concern regarding modern mining over the past two years.
The V2 stratum doesn’t change the concentration of the hashrate, but it does change who decides what goes into each block, which is something that really worries the Bitcoin community.
A single pool controlling more than 30% of the hashrate is far from ideal, because the same pool deciding the order of transactions for that share of blocks is the real risk people point to.
The protocol has existed since 2022, when Braiins and Spiral co-founded the working group. Until now, it had been treated as a niche side project with limited adoption. The membership of Foundry and AntPool gives it real scope, with the working group considering this decision as the start of a new phase of accelerated deployment.
The timeline also matches what the mining cohort as a whole is facing. CoinShares estimates that up to 20% of miners are currently unprofitable, with the hash price (the income a miner earns per unit of computing power) sitting at $38.57 per petahash per second per day, at or near break-even for operators running mid-generation hardware.
The difficulty is expected to increase again on May 15, from 132.47T to 135.64T, according to CoinWarz. The network hashrate now stands at 998 exahashes per second.
