Seven of the largest Bitcoin mining pools, representing roughly 75% of global hashrate, have joined the Stratum V2 working group, the protocol’s organizers said Monday. Foundry, AntPool, F2Pool, SpiderPool, MARA Pool, Block Inc., and DMND signed on to a standard that lets individual miners build their own block templates rather than accept transaction sets chosen by pool operators. The move marks the largest coordinated push to address transaction-level centralization in Bitcoin mining since the protocol’s 2022 launch, according to CoinDesk’s reporting on the announcement.
Stratum V2 is an open-source mining protocol that lets individual miners decide which transactions go into the blocks they hash, instead of delegating that choice to the pool operator.
- Seven pools accounting for about 75% of Bitcoin hashrate joined the Stratum V2 working group on May 11, 2026.
- Foundry alone runs 34.2% of global hashrate, with AntPool at 14.2% and F2Pool at 11.3%, per the working group’s figures.
- The protocol shifts block template construction from pool operators to individual miners, addressing censorship concerns.
- Braiins data cited by the group projects up to 7.4% profitability gains for miners from lower latency and improved fee capture.
Published: May 11, 2026 16:00 UTC
Why pool-level control became a problem
For more than a decade, mining pools have set the rules on what goes into each Bitcoin block. Individual miners contribute hashpower, but the pool operator decides which transactions get included and in what order. That arrangement made pools the de facto gatekeepers of the network’s transaction layer, even though no single operator controls a majority of hashrate today.
The concern sharpened in 2023 and 2024 when several pools began filtering specific transaction types tied to sanctioned addresses and to inscription-based protocols such as Ordinals. Critics argued the practice gave pool operators outsized power to shape what Bitcoin actually settles, undermining the network’s neutrality.
Stratum V2 attempts to separate the two functions. Pools still aggregate hashpower and pay miners, but miners can submit their own block candidates for the pool to validate. The change preserves the income-smoothing benefit of pooled mining while returning transaction selection to the operators of physical mining hardware.
What the 75% figure actually represents
The working group’s seven new signatories include the four largest pools by current hashrate, plus three smaller operators. According to figures cited by CoinDesk, Foundry contributes 34.2% of global Bitcoin hashrate, AntPool 14.2%, F2Pool 11.3%, and SpiderPool 10.5%. MARA Pool adds another 4.7%. Block Inc., parent of Square and Spiral, and DMND round out the list.
Joining the working group is a commitment to develop and eventually deploy the protocol, not an immediate switch. The seven pools are now formal participants in a process that started in 2022, when Braiins and Spiral co-founded the group as an independent open-source community. The signatories said in a joint statement carried by CoinDesk that the expanded membership begins “a new phase of accelerated deployment.”
What changes for miners and traders
For miners, the most concrete near-term effect is economic. The working group, citing Braiins research, said Stratum V2 can deliver up to 7.4% higher revenue through lower communication latency and better fee capture during periods of high mempool activity. Stratum V1, the protocol most pools still use, was designed when block subsidies dwarfed transaction fees. After two halvings, fees now represent a larger share of miner income, and milliseconds of latency translate into measurable revenue.
For traders and on-chain users, the implications are more structural. If individual miners build templates, no single pool operator can promise to censor a category of transactions, because the operator no longer decides what goes into the block. Selective inclusion would require coordinated action by many independent miners, which is harder to enforce and easier to detect.
The shift does not change hashrate concentration. Foundry and AntPool will continue to operate large pools, and individual miners are still economically dependent on them for payouts. What changes is the layer at which transaction policy is set.
Technical detail and deployment timeline
Stratum V2’s job negotiation feature is the mechanism that enables miner-side template construction. A miner builds a candidate block locally, including the transactions it wants to include, and submits the header and merkle root to the pool. The pool validates the work and pays out shares based on the proof-of-work submitted, but does not choose the transaction set.
The protocol also adds encrypted communication between miners and pools, which removes a long-standing attack surface where ISPs or middleboxes could observe and manipulate unencrypted Stratum V1 traffic.
The working group has not committed to a binding rollout schedule. Individual pools will decide their own timelines, and miners running older firmware will need updates from manufacturers including Bitmain and MicroBT before they can participate. The protocol has been usable in testnet form since 2023, and Braiins and a handful of smaller pools have run it in production for limited periods.
Regulatory and policy angle
U.S. and European regulators have repeatedly pressed mining pool operators to comply with sanctions screening, treating pools as the entity responsible for the transactions they include. A protocol that pushes that decision to individual miners complicates that enforcement model, because there is no single counterparty to subpoena.
The Office of Foreign Assets Control has not publicly commented on Monday’s announcement. The Stratum V2 working group’s documentation does not address sanctions compliance directly, framing the protocol as a technical neutrality measure rather than a policy statement.
Frequently asked questions
What is Stratum V2 in plain terms?
Stratum V2 is the updated communication protocol between Bitcoin miners and the pools that aggregate their hashpower. Its main change is letting individual miners pick the transactions in the blocks they mine, instead of leaving that choice to the pool operator. It also encrypts the traffic between miner and pool.
Does this announcement decentralize Bitcoin mining?
It decentralizes one specific function: choosing which transactions go into each block. Hashrate is still concentrated in a handful of large pools, and Foundry alone runs about a third of it. The change moves transaction-selection power from pool operators to the miners hashing under them, which is the part of mining centralization the Bitcoin community has flagged most often.
When will Stratum V2 actually be live across these pools?
The working group has not committed to a binding deadline. Each pool will set its own rollout timeline, and miner firmware from Bitmain, MicroBT, and other manufacturers needs to support the protocol before individual miners can use job negotiation. Braiins and several smaller operators have run Stratum V2 in production already, but broad deployment will likely play out over the next 12 to 24 months.
