Foundry backs Stratum V2 in mining overhaul

Seven pools covering 75% of Bitcoin hashrate have joined Stratum V2, shifting block control to individual miners.

Seven of the world’s largest Bitcoin mining pools have joined the Stratum V2 working group, giving the open protocol a combined hashrate share of nearly 75%. Foundry, AntPool, F2Pool, SpiderPool, MARA Pool, Block Inc., and DMND are all now backing the standard.

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. The Stratum V2 working group announced the new members last week.

Why this shift matters for Bitcoin

Under the current Stratum V1 standard, pool operators decide which transactions go into every block. Individual miners have no say, and that concentration has been the loudest structural concern modern Bitcoin mining has faced.

Stratum V2 does not reduce hashrate concentration. The same large pools still command the same share of computing power. What changes is who decides the contents of each block, separating the two risks that previously compounded each other.

AntPool CEO Andy Zhou said the company is “proud to support the broader adoption of Stratum V2,” adding that an open, interoperable standard lets the industry collaborate on efficiency, security, and decentralization.

Timing and mining economics

The announcement lands during a difficult stretch for the industry. CoinShares estimated that up to 20% of the global Bitcoin mining fleet may be operating unprofitably under current conditions.

Network difficulty is set to rise again on May 15, climbing from 132.47T to 135.64T. Tether has separately been building its own open-source Mining Development Kit to unify hardware management across fleets, adding another layer of infrastructure competition as pools race to modernise their technology stacks.