Builder Market Share

Builder Market Share measures the percentage of blocks added to the Ethereum blockchain that were constructed by a particular block builder within a defined timeframe, such as daily, weekly, or monthly. Following Ethereum's transition to Proof-of-Stake and the adoption of PBS, specialized builders compete to create the most profitable blocks by aggregating user transactions and MEV (Maximal Extractable Value) opportunities. The entity that wins this auction, typically the builder offering the highest bid to the block proposer (validator), gets its block included in the chain. Market share is thus a direct indicator of a builder's competitiveness and dominance in this critical, revenue-generating layer of the network.

A builder's share is calculated by tracking the builder_pubkey field in block headers. Analysts aggregate this data to rank entities like Flashbots, Titan, and rsync by their contribution to chain production. High market share signifies several advantages: greater economies of scale in MEV extraction, stronger relationships with searchers who supply profitable transaction bundles, and potentially more reliable revenue for validators who choose their blocks. However, concentrated market share raises concerns about centralization, as a dominant builder could theoretically influence transaction inclusion, censorship resistance, and the overall economic fairness of the network.

Monitoring this metric is crucial for network health analysis. A highly concentrated builder landscape, where one or two entities control a majority of blocks, presents systemic risks. Consequently, builder market share is a primary datapoint informing discussions around PBS enshrinement and the development of credible neutrality in block construction. For developers and DeFi users, understanding which builders are dominant can provide insight into potential transaction censorship patterns or the prevalence of certain types of MEV, such as arbitrage or liquidations, within their applications.

Builder market share is most commonly measured by the percentage of blocks a specific builder successfully has included in the canonical chain over a defined period. This is the primary, high-level metric. Analysts track this data across epochs or days, often visualizing it on dashboards from firms like EigenPhi, Relayoor, and mevboost.pics. A builder's share is calculated by dividing the number of blocks it built and won by the total number of blocks produced in that timeframe. This reveals which entities are most successful in the competitive auction held by relays.

The raw block count, however, only tells part of the story. A more nuanced analysis examines the value of the blocks won. This involves measuring the total ETH or USD value of priority fees and MEV (Maximal Extractable Value) captured by the builder's blocks. A builder with a smaller share by count but a larger share by value may be specializing in high-value, complex MEV opportunities. Furthermore, market share is often segmented by relay, as builders may have dominant positions on specific relays (e.g., BloXroute, Flashbots, Ultrasound) but not others, highlighting dependencies within the PBS supply chain.

Beyond simple output, measurement must account for censorship resistance. A key metric is the percentage of blocks that comply with OFAC sanctions by excluding transactions from sanctioned addresses. Builders with high market share that also produce a high percentage of compliant blocks increase the network's censorship risk. Therefore, a complete market share analysis evaluates both quantity (blocks produced) and quality (value extracted and compliance status). This dual lens is essential for stakeholders assessing network health and decentralization.

Data collection for these metrics relies on parsing public blockchain data and the public mempool. Tools monitor the fee_recipient field and other builder-specific identifiers in block headers to attribute production. Challenges in measurement include the obfuscation of builder identity and the potential for builders to use multiple public keys. Despite this, consistent tracking over time provides a reliable picture of competitive trends, the entry of new builders, and the impact of software updates or strategic shifts in the MEV landscape.

In practice, builder market share is highly dynamic. It can shift rapidly due to changes in builder software efficiency, strategic bidding behavior, exclusive relationships with large searchers or validators, and adjustments to relay policies. For example, the emergence of a new, more efficient MEV strategy can propel a builder's share upward quickly. Consequently, these metrics are not static reports but are used for real-time monitoring and long-term trend analysis to inform protocol development, regulatory discussion, and validator operator decisions.

In a Proof-of-Stake (PoS) or proposer-builder separation (PBS) model, builder market share quantifies the proportion of blocks produced by a specific entity or group of entities known as block builders. These builders are responsible for constructing the most profitable or desirable blocks by selecting and ordering transactions from the mempool. A high concentration of market share among a few builders can indicate centralization risks, potentially leading to censorship, MEV extraction advantages, and reduced network resilience. This metric is foundational for assessing the health of a blockchain's consensus layer.

The distribution of builder market share directly impacts network security and fairness. A decentralized builder set makes it more difficult for any single actor to manipulate transaction ordering for maximal extractable value (MEV) or to censor specific transactions. Conversely, when a builder like Flashbots or a relay-aligned entity commands a dominant share, it can create central points of failure and influence the fee market. Analysts track this share over time to monitor trends, such as the rise of solo stakers using services like EigenLayer or the consolidation of power among professional searchers and validators.

For developers and decentralized application (dApp) teams, builder concentration has practical implications. Transactions may experience variable confirmation times or costs depending on the builder's inclusion policies. Protocols concerned with credible neutrality often monitor builder market share to ensure their users are not subject to discriminatory practices. Furthermore, the evolution of encrypted mempools and suave-type architectures aims to redistribute power away from centralized builders, making this metric a key indicator of technological and economic progress within the blockchain stack.

Builder market share quantifies the proportion of blocks produced by different block builders within a proposer-builder separation (PBS) framework, such as Ethereum's post-merge architecture. This metric is a critical indicator of decentralization and potential censorship risks at the block construction layer. A highly concentrated market, where a few builders dominate, can lead to MEV centralization and increase the network's vulnerability to regulatory pressure or coordinated filtering of transactions. Analysts track this share over time to assess the health of the builder ecosystem.

The evolution of builder market share is driven by several key factors: the sophistication of a builder's MEV (Maximal Extractable Value) extraction strategies, their relay relationships, and their operational reliability. Builders that consistently create more profitable blocks—by optimally ordering transactions and capturing arbitrage opportunities—are favored by validators (block proposers) seeking to maximize their rewards. This has led to the rise of specialized, often vertically integrated entities that combine searcher capabilities, proprietary order flow, and high-performance infrastructure.

Current trends show a persistent tension between centralization pressures and efforts to foster a more distributed builder landscape. While a small cohort of professional builders like Flashbots, BloXroute, and Titan often command significant share, initiatives like SUAVE (Single Unified Auction for Value Expression) aim to democratize access to block building. Furthermore, the adoption of inclusion lists and other crlist-like mechanisms by proposers can mitigate builder power by guaranteeing transaction inclusion, directly impacting how market share translates into control over the chain's content.