Bitcoin (BTC) mining pools with 75% of hashrate back open standard for block construction

The biggest decentralization move bitcoin mining has seen in years just happened quietly, with seven of the largest pools agreeing to back 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 the individual miners in those pools. The biggest practical change it introduces is letting individual miners construct their own block templates, meaning the choice of which transactions get included in each new block sits with the miner rather than whoever operates the pool.

Foundry alone controls 34.2% of global bitcoin hashrate, AntPool another 14.2%, F2Pool 11.3%, and SpiderPool 10.5%, with MARA Pool adding 4.7%, per Hashrate Index data. Together with the rest of the Stratum V2 signatories, the seven pools now backing the standard represent close to 75% of all bitcoin hashrate.

Under the current Stratum V1 standard, the transaction selection for nearly every new block sits with the pool operators rather than the individual miners actually doing the work. That concentration has been the loudest structural concern about modern mining for the past two years.

Stratum V2 does not change hashrate concentration, but it does change who decides what goes into each block, which is the part the Bitcoin community actually worries about.

A single pool controlling more than 30% of hashrate is less than ideal, as the same pool deciding the transaction order for that share of blocks is the actual 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. Foundry and AntPool joining gives it real reach, with the working group framing the move as the start of a new phase of accelerated deployment.

The timing also matches what the broader mining cohort is dealing with. CoinShares estimates up to 20% of miners are currently unprofitable, with hashprice (the revenue a miner earns per unit of computing power) sitting at $38.57 per petahash per second per day, at or near breakeven for operators running mid-generation hardware.

Difficulty is set to rise again on May 15 from 132.47T to 135.64T, per CoinWarz. Network hashrate now sits at 998 exahash per second.