The landscape of decentralized finance and distributed ledger technology has long grappled with a fundamental question: how can the industry objectively measure the degree of decentralization within a network? On September 1, a landmark joint study published by ARK Invest and Glassnode, titled "The Decentralization Spectrum," introduced a rigorous framework for quantifying "capture risk." This metric defines the smallest group of block-production entities required to cross a protocol-relevant control threshold, effectively providing a mathematical snapshot of a network’s vulnerability to collusion or censorship.

The report’s findings have sparked significant discussion among institutional investors and protocol architects. According to the scorecard, the threshold for a critical disruption of consensus stands at just three entities for both Bitcoin and Ethereum, while Solana requires a coalition of 19 (a figure that shifted to 18 in real-time data as of September 6). While these numbers suggest Solana might be more resilient to coordination-based attacks, the report simultaneously ranked Bitcoin first in its composite decentralization ranking. This apparent contradiction highlights the multi-dimensional nature of blockchain security, where the number of entities required to disrupt consensus is only one measure of risk, balanced against ownership distribution, infrastructure independence, software diversity, and the speed at which participants can exit the network.

The Methodology of Critical Resilience Thresholds

The core of the ARK Invest and Glassnode report centers on what is termed the "critical resilience threshold." This metric seeks to identify how many of the largest entities in a network must coordinate to reach a concentration point that governs block production or voting power. However, the inputs for this calculation vary significantly across different consensus mechanisms.

In the Bitcoin network, which utilizes Proof of Work (PoW), the weight is assigned to the hash rate attributed to specific mining pools. For Ethereum and Solana, both of which utilize Proof of Stake (PoS) variations, the weight is assigned to the amount of stake controlled by various entities. The complexity of this measurement is compounded by the taxonomy of these entities; a single label in a staking dashboard might represent a decentralized liquid-staking protocol, a centralized exchange, a distributed validator network, or a solo validator.

To understand the 3/3/19 result, one must examine the specific protocol rules. In Bitcoin, three mining pools—Foundry USA, AntPool, and F2Pool—collectively control more than 50% of the network’s hash rate. In Ethereum, a similar concentration exists among top staking providers. In Solana, the "Nakamoto Coefficient" is used to measure the number of validators required to reach 33.4% of the total stake, the threshold necessary to stall the network or censor blocks.

Bitcoin: Hash Rate Concentration versus Miner Mobility

A deep dive into Bitcoin’s metrics reveals a nuanced relationship between mining pools and decentralization. As of September 6, a seven-day snapshot of Bitcoin mining data attributed 26.88% of blocks to Foundry USA, 16.91% to AntPool, and 15.25% to F2Pool. Together, these three entities coordinated block templates for 59.04% of the network’s production.

However, the ARK-Glassnode framework distinguishes between pool share and miner ownership. Unlike PoS validators, Bitcoin miners provide computational work to a pool coordinator but retain ownership of the underlying hardware. The report estimates that an individual miner could exit a 1% position in the Bitcoin network in approximately 30 seconds simply by redirecting their hash rate to a different pool or switching off their hardware.

This high degree of "exit fluidity" means that while mining pool concentration is a valid metric for monitoring short-term censorship or template selection risks, the ultimate control of the network remains highly dispersed. This mobility is a primary reason why Bitcoin maintains the top spot in composite decentralization rankings despite its low entity count for consensus coordination.

Ethereum: The Taxonomy of Staking and Protocol Thresholds

Ethereum presents a different challenge in classification. The rise of liquid staking and professional node operators has blurred the lines of what constitutes a "single entity." Data from Rated Network, a validator analytics provider, showed that as of early September, Lido accounted for 21.17% of the stake, followed by SSV at 16.56% and Binance at 7.77%.

The report notes that a single label like "Lido" can be misleading. While it appears as one entity on a chart, it is a protocol comprised of 544 distinct node operators. This layered structure provides a buffer against certain types of capture but introduces other risks related to smart contract vulnerabilities or governance attacks.

Furthermore, Ethereum’s threat model is tiered based on the percentage of stake controlled by a malicious coalition:

• 33% of Stake: Can be used to delay finality, preventing the network from reaching an irreversible state.
• 50% of Stake: Allows for the censorship of transactions and control over short-range fork choices.
• 66% of Stake: Provides the power to finalize a preferred chain and potentially alter finalized history.

The ARK-Glassnode report’s count of three entities refers to the threshold required to reach the most immediate disruption point, emphasizing the need for continued vigilance regarding staking concentration.

Solana: High Throughput and the Nakamoto Coefficient

Solana’s result of 19 entities (updated to 18 on some dashboards by September 6) reflects its specific architectural design. Solana utilizes a Nakamoto Coefficient to measure the minimum number of validators whose combined stake reaches 33.4% of total voting power. According to Solana Compass, an independent network dashboard, this coefficient has fluctuated between 18 and 20 throughout 2024 and 2025.

The Solana Foundation’s health report, published in June 2025 using data from April 2025, recorded a coefficient of 20. This suggests that Solana requires a larger coalition of top-tier validators to coordinate a disruption than Bitcoin or Ethereum. However, this resilience at the validator level is offset by other dependencies.

High-throughput networks like Solana require significant hardware resources, often leading validators to cluster in commercial data centers. The Solana Foundation noted that while there are over 100 hosting providers, two entities—TeraSwitch and Latitude—host approximately 45.70% of the network’s stake. This infrastructure concentration creates a correlated failure mode where a single ISP outage or a jurisdictional regulatory action could impact nearly half the network, regardless of how many individual validators are involved.

Correlated Failure Modes: Hosting and Software Diversity

A critical enrichment of the ARK-Glassnode study is its focus on dependencies that exist outside of consensus participation. Infrastructure, geography, and software create "hidden" avenues for network capture or failure.

Node Hosting and Visibility:
The report highlighted that 63% of Bitcoin nodes operate behind the Tor network, providing significant geographic resilience and privacy. However, different crawlers yield different results; data from Clark Moody’s dashboard on September 6 showed only 48.3% Tor usage among reachable nodes. For Ethereum, hosting data is similarly fragmented. While the report cited 20% of nodes on Amazon Web Services (AWS), other trackers like Ethernodes suggest the number may be lower when accounting for various ISP labels.

Client Software Diversity:
Client diversity is a primary defense against software bugs that could take down an entire network. Ethereum has made strides in this area, though Geth still maintains a significant presence at 50.17% of execution clients. Solana faces a steeper challenge; as of April 2025, approximately 92% of the stake was using the Agave/Jito codebase. The emergence of Firedancer and the hybrid Frankendancer client (accounting for about 7% of stake) represents a vital step toward reducing the blast radius of a potential software-level failure.

Exit Speed and Market Liquidity

The ability for a participant to leave a network during a period of coercion or failure is a vital metric for institutional fiduciaries. The ARK-Glassnode report identifies a stark contrast between Bitcoin and PoS networks in this regard.

Bitcoin miners can redirect work almost instantaneously. In contrast, Ethereum validators must navigate a rate-limited exit queue. Under normal conditions, this queue might be empty, with a withdrawal estimate of roughly one day. However, during periods of extreme network stress or mass exits, the queue can extend to several weeks. While liquid-staking tokens (LSTs) provide a market-based exit route, they are subject to market liquidity and can de-peg from the underlying asset during crises.

Institutional Implications and Analysis

The joint scorecard from ARK Invest and Glassnode serves as a sophisticated guide for institutions considering blockchains as settlement infrastructure. The report suggests that fiduciaries must define the specific failure they need to survive before selecting a network based on a single metric.

For an institution concerned with long-term censorship resistance and the ability to audit the entire ledger from a home office, Bitcoin’s high scores in auditability and hardware mobility make it the preferred choice. For an institution prioritizing high-speed transaction finality and a higher threshold for validator-level collusion, Solana’s 19-entity coefficient offers a compelling argument, provided the institution accounts for data center concentration.

Ultimately, the "3/3/19" result is not a final grade but a starting point for a deeper risk assessment. True decentralization is a spectrum that involves:

1. Coordination Risk: How many people must agree to break the rules?
2. Infrastructure Risk: Where are the machines, and who owns the pipes they run on?
3. Software Risk: Is the entire network running on a single codebase?
4. Exit Risk: If the network is compromised, how fast can I get my capital out?

As the digital asset industry matures, the ARK-Glassnode framework provides the necessary vocabulary to move beyond marketing claims and toward a data-driven understanding of blockchain resilience. The tension between different forms of network exposure—whether through mining pools, staking protocols, or cloud providers—will continue to shape the development of these protocols as they vie for a role in the global financial system.