Seven of the largest Bitcoin mining pools have publicly joined the Stratum V2 working group, marking a significant shift toward decentralization in how transaction blocks are constructed. Foundry, AntPool, F2Pool, SpiderPool, MARA Pool, Block Inc., and DMND now back the open-source protocol, bringing approximately 75% of global Bitcoin hashrate into the initiative.
The announcement comes as miners face increasingly difficult operating conditions. Bitcoin mining difficulty is projected to rise from 132.47 T to 135.64 T on May 15, according to CoinWarz data, squeezing margins further. CoinShares estimates up to 20% of miners are already unprofitable, with hashprice—the daily revenue per petahash per second—hovering between $36 and $38.57, barely above breakeven for many operators.
Stratum V2, co-founded in 2022 by Braiins and Spiral, redesigns how pools communicate with individual miners. Its core innovation allows miners to construct their own block templates, directly selecting which transactions to include, rather than relying on pool operators. Under the current Stratum V1 standard, pool operators have near-total control over block composition, raising long-standing concerns about centralization and potential transaction censorship.
Foundry alone controls around 34% of hashrate, AntPool another 14–17%, F2Pool 11.3%, SpiderPool 10.5%, and MARA Pool 4.7%, per Hashrate Index. Even though the new protocol does not reduce hashrate concentration itself, it redistributes decision-making power away from a handful of pool operators. Industry participants note this addresses the main structural worry—transaction selection control—rather than just hashrate distribution.
The adoption signals that protocol-level efficiency is now a competitive priority. Large pools can use it to retain miners by offering better performance and autonomy, while smaller miners gain bargaining power and reduce lock-in with closed systems. As difficulty rises and energy costs bite, even slight latency reductions or flexibility in block template choice can affect whether a miner captures a block reward.
The working group describes the enlistment of these major pools as the start of a new phase of accelerated deployment. If integrated broadly, Stratum V2 could enhance transparency and limit the outsized influence of dominant pools over Bitcoin’s transaction history, without altering the network’s core reward economics.
