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How Exclusive are Ethereum Transactions? Evidence from non-winning blocks

Vabuk Pahari, Andrea Canidio

TL;DR

The paper addresses how Proposer-Builder Separation (PBS) in Ethereum concentrates influence among builders by examining exclusive versus private transaction flow. It analyzes a large dataset of 15,097 blocks from Agnostic Relay over 28 bidding cycles, classifying transactions as Public, Private, or Exclusive using public mempool data and transaction logs. The key finding is that exclusive transactions account for roughly 77.2%–84% of fees in winning blocks, even though they are fewer in number, while exclusive sender–builder relationships explain only about 7% of the value of exclusive transactions when focusing on on-chain outcomes. The work demonstrates that exclusivity is a major driver of PBS dynamics and potential competition concerns, with notable implications for user safety due to delays and attacks, and it lays groundwork with a companion study exploring user impact and arbitrage activity.

Abstract

We analyze 15,097 blocks proposed for inclusion in Ethereum's blockchain over an eight-minute window on December 3, 2024, during which 38 blocks were added to the chain. We classify transactions as exclusive -- appearing only in blocks from a single builder -- or private -- absent from the public mempool but included in blocks from multiple builders. We find that, depending on the methodology, exclusive transactions account for between 77.2% and 84% of the total fees paid by transactions in winning blocks. Moreover, we show that exclusivity cannot be fully attributed to persistent relationships between senders and builders: only between 7% and 8.4% of all on-chain exclusive transaction value originates from senders who route exclusively to one builder. Finally, we observe that transaction exclusivity is dynamic. Some transactions are exclusive at the start of a bidding cycle but later appear in blocks from multiple builders. Other transactions remain exclusive to a losing builder for two or three cycles before appearing in the public mempool. These transactions are therefore delayed and then exposed to potential attacks.

How Exclusive are Ethereum Transactions? Evidence from non-winning blocks

TL;DR

The paper addresses how Proposer-Builder Separation (PBS) in Ethereum concentrates influence among builders by examining exclusive versus private transaction flow. It analyzes a large dataset of 15,097 blocks from Agnostic Relay over 28 bidding cycles, classifying transactions as Public, Private, or Exclusive using public mempool data and transaction logs. The key finding is that exclusive transactions account for roughly 77.2%–84% of fees in winning blocks, even though they are fewer in number, while exclusive sender–builder relationships explain only about 7% of the value of exclusive transactions when focusing on on-chain outcomes. The work demonstrates that exclusivity is a major driver of PBS dynamics and potential competition concerns, with notable implications for user safety due to delays and attacks, and it lays groundwork with a companion study exploring user impact and arbitrage activity.

Abstract

We analyze 15,097 blocks proposed for inclusion in Ethereum's blockchain over an eight-minute window on December 3, 2024, during which 38 blocks were added to the chain. We classify transactions as exclusive -- appearing only in blocks from a single builder -- or private -- absent from the public mempool but included in blocks from multiple builders. We find that, depending on the methodology, exclusive transactions account for between 77.2% and 84% of the total fees paid by transactions in winning blocks. Moreover, we show that exclusivity cannot be fully attributed to persistent relationships between senders and builders: only between 7% and 8.4% of all on-chain exclusive transaction value originates from senders who route exclusively to one builder. Finally, we observe that transaction exclusivity is dynamic. Some transactions are exclusive at the start of a bidding cycle but later appear in blocks from multiple builders. Other transactions remain exclusive to a losing builder for two or three cycles before appearing in the public mempool. These transactions are therefore delayed and then exposed to potential attacks.

Paper Structure

This paper contains 11 sections, 1 figure, 5 tables.

Table of Contents

  1. Introduction
  2. Summary of results.
  3. Relevant literature
  4. Background on PBS
  5. Dataset
  6. Results
  7. Logs-based classification
  8. Relationship between searchers and builders
  9. Transactions' transitions.
  10. Conclusion
  11. Additional tables

Figures (1)

  • Figure 1: Exclusive, non-exclusive (public and private), and non-identified transactions for each winning block. For each block, we report both the share of transactions and the share of total fees attributable to each category. Blocks are numbered 21,322,622 through 21,322,660.