Bitcoin Mining Decentralizes 75% of Hashrate Backs Stratum V2 in 2026

Seven of the world’s largest Bitcoin mining pools — collectively controlling 75% of the network’s global hashrate — announced on May 7, 2026 that they are joining the Stratum V2 working group. The move marks the most significant structural shift in Bitcoin mining in over a decade, redistributing the power to decide which transactions enter each new block from pool operators down to individual miners.

The Status Quo: Why Stratum V1 Was a Centralization Problem

For more than 14 years, Bitcoin’s mining infrastructure has run on Stratum V1, a protocol introduced around 2012 to let miners pool computing resources and share block rewards. It solved a real coordination problem: solo miners face enormous variance in reward timing, while pooled mining smooths income and makes the economics sustainable for most participants.

But Stratum V1 came with a hidden centralization trade-off. Under the original design, pool operators — not the miners doing the actual computational work — control which transactions get included in each new block. Every time a pool finds a valid block, the set of transactions inside it was chosen by the pool’s server, not by the thousands of individual miners contributing hashrate.

This matters because it concentrates enormous structural power at the pool level. A pool operator could theoretically choose to censor certain transactions, favor certain counterparties, or comply with government orders to exclude specific addresses — all without miners having any direct say. For a system designed to be permissionless and censorship-resistant, that is a meaningful vulnerability.

Stratum V2 was designed specifically to fix this. The protocol, developed by Braiins and Spiral (Block Inc.'s open-source division) starting in 2022, introduces a Job Declaration sub-protocol that allows individual miners to construct their own block templates. Pool operators no longer have exclusive control over what goes into the blocks their miners are building.

Seven Pools, 75% of Hashrate

The working group’s announcement named seven major pools that have now joined the Stratum V2 effort:

• Foundry — 34.2% of global Bitcoin hashrate
• AntPool — 14.2%
• F2Pool — 11.3%
• SpiderPool — 10.5%
• MARA Foundation — 4.7%
• Block Inc. (co-founder of the working group)
• DMND (already operating in production since 2025)

Foundry alone controls more than a third of the entire Bitcoin network’s computing power, making its participation decisive. Combined, the seven pools represent a critical mass capable of setting a new industry standard rather than leaving Stratum V2 as a niche alternative for technically minded operations.

AntPool CEO Andy Zhou said the company was “proud to support the broader adoption of Stratum V2” and emphasized open standards as essential for “efficiency, security, and decentralization.” SpiderPool CTO Kenway Wang highlighted that the protocol’s miner-constructed templates are “especially useful for operators in bandwidth-constrained environments,” pointing to practical global deployment advantages beyond the philosophical decentralization case.

Block Inc.'s involvement is structurally important beyond just its pool membership. The company’s hardware manufacturing arm is positioned to embed Stratum V2 support directly at the chip level — meaning future mining hardware could ship with native support, making adoption automatic rather than an active choice operators must make.

What Actually Changes Under Stratum V2

Stratum V2 is a complete protocol replacement, not an incremental patch on V1. Beyond transaction selection, several technical changes address long-standing weaknesses in mining infrastructure.

Encryption: Stratum V1 transmits mining data in plaintext, leaving communications between miners and pool servers exposed to eavesdropping and potential manipulation. Stratum V2 introduces end-to-end authenticated encryption across the full connection, closing an attack vector that has existed since the protocol launched.

Bandwidth efficiency: The protocol is significantly more efficient on the wire. According to the working group, pool-side bandwidth drops by approximately 60%, while individual miners see roughly 70% reduction in their own bandwidth usage. For large operations with hundreds or thousands of ASICs running constantly, this translates directly into lower operating costs and improved performance in latency-sensitive environments.

No mandatory hardware upgrade: One barrier to adoption in the past was the concern that miners would need new firmware or hardware to use Stratum V2. The working group addressed this with translation proxies that allow V1-firmware devices to communicate via the V2 protocol without requiring updates. This removes the upgrade friction that could otherwise slow deployment across an industry built on specialized, expensive hardware with long replacement cycles.

Job Declaration sub-protocol: This is the centerpiece of the decentralization improvement. Rather than pool servers selecting transactions and handing miners a pre-built block template to hash, the Job Declaration protocol lets miners specify their own transaction sets. The pool validates the work and coordinates reward sharing, but the transaction composition comes from the miner — inverting the control structure that has existed under V1.

Transaction Censorship Resistance: The Core Benefit

The practical implication of miner-selected block templates is that Bitcoin becomes substantially more censorship-resistant at the infrastructure level.

Under Stratum V1, a government order, regulatory pressure, or a pool operator’s commercial decision could result in certain transactions being systematically excluded. Because five major pools currently control roughly 70% of global hashpower, compliant operators at those pools could suppress transactions from a targeted address or protocol without needing to compromise the Bitcoin protocol itself — just the pool software.

With Stratum V2’s Job Declaration enabled, the equation changes. Even if a pool’s management wanted to censor specific transactions, miners contributing hashrate could simply include those transactions in their own templates. The pool would still coordinate block submission and reward distribution, but would no longer be the single chokepoint for transaction selection.

This shifts Bitcoin closer to its original design intent: a system where no single entity controls who can transact. Mining pools remain necessary for income smoothing, but their structural power over transaction ordering gets substantially reduced.

DMND, which launched in 2025 as the first pool offering full miner-selected templates in production, has already demonstrated that the technical model works at scale. The May 7 announcement brings the rest of the industry’s dominant pools into alignment with what DMND proved was viable.

What Miners Gain: Profitability and Security

Beyond the network-level benefits, Stratum V2 offers direct economic incentives for individual miners.

The working group projects up to 7.4% higher profitability for miners through a combination of reduced latency, improved fee capture, and more efficient data handling. In mining, where profit margins depend on razor-thin spreads between electricity costs and block rewards, a 7.4% improvement in realized returns is substantial.

The fee capture angle is particularly notable. Under V1, pool operators selecting transactions also control which fee-bearing transactions end up in a block. Miners constructing their own templates can prioritize high-fee transactions directly, aligning their block construction choices with their own economic interests rather than the pool operator’s preferences.

Security improvements under the encryption upgrade matter operationally as well. Attacks on mining communications — while not common — have been a known risk under V1’s plaintext model. End-to-end encryption eliminates this class of attack entirely.

For smaller mining operations and those in emerging markets where bandwidth costs are a real constraint, the 60–70% bandwidth reduction can meaningfully affect operating economics in ways that aggregate to significant savings at scale.

What This Means for Bitcoin Investors

The Stratum V2 transition is a longer-term structural development rather than a near-term price catalyst. But its implications for Bitcoin’s investment thesis are real.

Bitcoin’s value proposition rests heavily on properties that are difficult to replicate: censorship resistance, permissionless access, and decentralization of control. The Stratum V1 regime introduced a structural gap between Bitcoin’s stated properties and its operational reality — one where a handful of pool operators held de facto veto power over transaction inclusion.

Stratum V2, adopted by pools controlling 75% of global hashrate, begins to close that gap. The result is a Bitcoin network that is architecturally more aligned with its core guarantees. For institutional investors performing due diligence on Bitcoin’s censorship resistance — a growing concern as regulatory pressures mount globally — this development addresses a legitimate structural risk.

For retail investors and Bitcoin holders, the transition is also significant as a signal about the mining industry’s direction. The voluntary coordination of competing pools — Foundry, AntPool, F2Pool, and SpiderPool compete directly for hashrate — around an open standard that reduces their own control over block construction is not a trivial commercial decision. It reflects industry consensus that Bitcoin’s long-term value depends on maintaining the decentralization that makes it uniquely valuable.

Full implementation across all participating pools will take time, and the DMND model shows the technology is production-ready now. With Block Inc. positioned to embed Stratum V2 at the hardware level for future ASIC generations, the transition looks increasingly like a matter of when rather than whether.

Key Takeaways

• Seven pools representing 75% of global hashrate joined the Stratum V2 working group on May 7, 2026: Foundry (34.2%), AntPool (14.2%), F2Pool (11.3%), SpiderPool (10.5%), MARA Foundation (4.7%), Block Inc., and DMND.
• Transaction selection shifts from pool operators to individual miners under the Job Declaration sub-protocol.
• End-to-end encryption replaces Stratum V1’s 14-year-old plaintext architecture.
• Up to 7.4% profitability gain projected for miners via lower latency and better fee capture.
• No hardware upgrade required — translation proxies allow existing V1 firmware to connect via V2.
• DMND has been running Stratum V2 in production since 2025, proving the model viable before this week’s broader adoption signal.

For long-term Bitcoin holders, this is the mining infrastructure story to watch in 2026. The shift does not change Bitcoin’s price trajectory in the short run — but it materially strengthens the network properties that underpin its long-run value case.