Seven of the world’s largest bitcoin mining pools, collectively controlling nearly 75% of global hashrate, have formally joined the Stratum V2 working group in what amounts to the most significant decentralization move in mining in years. Foundry, AntPool, F2Pool, SpiderPool, MARA Pool, Block Inc, and DMND all signed on to the open-source protocol standard, the group announced last week.
The development shifts a foundational piece of Bitcoin’s block construction process away from pool operators and back toward the individual miners who actually contribute the computing power. That change addresses one of the loudest structural concerns in the industry over the past two years.
Who Controls What Goes Into Each Block
Under the existing Stratum V1 standard, pool operators decide which transactions get bundled into every new block their pool produces. That means a handful of companies have quietly held enormous influence over transaction selection across the network.
Stratum V2 replaces that arrangement by letting individual miners construct their own block templates, choosing which transactions to include before submitting work to the pool.
The hashrate figures behind this shift are substantial. According to Hashrate Index data, Foundry alone accounts for 34.2% of global bitcoin hashrate, with AntPool at 14.2%, F2Pool at 11.3%, and SpiderPool at 10.5%.
MARA Pool contributes another 4.7%, and together with the remaining signatories the seven pools represent close to three quarters of all bitcoin mining output.
Stratum V2 does not reduce hashrate concentration at the pool level. Foundry still controls more than a third of the network, and that number is unchanged.
What changes is the governance question the Bitcoin community has pointed to as the real risk: a single pool dictating the transaction order for that share of blocks.
From Niche Project to Network Standard
The protocol has existed since 2022, when Braiins and Spiral co-founded the working group. For most of that period it was treated as a technically sound but practically overlooked side project with limited real-world adoption among major pools.
Foundry and AntPool joining changes that calculus entirely. The two pools together account for nearly half of global hashrate, and their participation gives the standard the critical mass needed for genuine network-wide adoption.
The working group framed the announcements as the beginning of a broader rollout rather than a completed transition.
The timing also reflects the difficult economics many miners are navigating. An estimated 20% of mining operations are currently running unprofitably as network difficulty and total hashrate continue to climb following the April 2024 halving.
In that environment, protocol improvements that reduce operational friction and restore miner autonomy carry added weight.
For Bitcoin’s broader security model, the shift matters beyond economics. Transaction censorship risk, the ability of a pool to selectively exclude or delay certain transactions, has been the central concern that Stratum V2 was designed to address.
With three quarters of hashrate now formally behind the standard, that risk becomes considerably harder to execute even by the largest individual pools.
Not Financial Advice: This article is for informational purposes only. Crypto investments are highly volatile. Always do your own research.
