LibraryMarkets2019Design paperCorpus record
Flash Boys 2.0: Frontrunning, Transaction Reordering, and Consensus Instability in Decentralized Exchanges
Flash Boys 2.0. Philip Daian, Steven Goldfeder, Tyler Kell, Yunqi Li, Xueyuan Zhao, Iddo Bentov, Lorenz Breidenbach and Ari Juels.
A measurement paper. Miners and bots reorder and insert transactions around DEX trades. The authors name miner-extractable value and show priority gas auctions. It is not a trading manual, and it is not a claim that any strategy here is available or profitable now.
Flash Boys 2.0 measures how public Ethereum transactions were reordered around early DEX trades. Whoever can order the block can take value from the trade. If that value exceeds the block reward, the chain's own consensus can be bid for.
- Evidence
- Primary paper
- Re-measured
- No
- Assumptions
- 4
- Records linked
- 5
Code
Source, repository, and what is actually hosted
- arXiv:1904.05234https://arxiv.org/abs/1904.05234
- The source URL is not a GitHub repository. No code remote is invented.
- Full text is not mirrored. Public availability is not a licence to copy the file onto this site.
- Add to a reading list
01 Claim ledger
What the paper is allowed to say
Each row is a sentence already in the study. The status is the same on every row: a model claim, not a live measurement.
Claim 01 · Paper model
The mempool is a broadcast of intent
A transaction sitting in public view is an option on its own execution. A searcher can buy before it and sell after it, or bid to land next to it. The paper records that auction in gas prices.
Claim 02 · Paper model
The producer is the auctioneer
Miners, in the 2019 setting, choose inclusion and order. The profit is not a fee the protocol printed. It is the difference a reorder can extract from users who already submitted.
Claim 03 · Paper model
Time-bandit is the consensus claim
If reordering old blocks pays more than the reward for extending the tip, a rational miner rewrites history. The paper's warning is about consensus stability, not about a particular bot.
Claim 04 · Paper model
This is not a how-to
The study names the incentive. It does not specify a sandwich, a bundle format, or a current profit. Those details change, and copying them is not what this library is for.
02 Three cuts
Observation, model, falsifier
A desk does not stop at the summary. Each claim is cut three ways, using only this study's own assumptions and checks. Nothing here is a new figure.
01 The mempool is a broadcast of intent
Observation
What the study says
A transaction sitting in public view is an option on its own execution. A searcher can buy before it and sell after it, or bid to land next to it. The paper records that auction in gas prices.
Model
What has to hold
The measurements are about the exchanges and the period the paper studied. They are not a current volume figure.
Falsifier
What would retire it
Are intents public before they execute?
02 The producer is the auctioneer
Observation
What the study says
Miners, in the 2019 setting, choose inclusion and order. The profit is not a fee the protocol printed. It is the difference a reorder can extract from users who already submitted.
Model
What has to hold
Block producers can order transactions. A protocol that removes that discretion removes this specific auction.
Falsifier
What would retire it
Who chooses transaction order, and can that right be sold?
03 Time-bandit is the consensus claim
Observation
What the study says
If reordering old blocks pays more than the reward for extending the tip, a rational miner rewrites history. The paper's warning is about consensus stability, not about a particular bot.
Model
What has to hold
The measurements are about the exchanges and the period the paper studied. They are not a current volume figure.
Falsifier
What would retire it
Is the extractable value comparable to the protocol reward?
04 This is not a how-to
Observation
What the study says
The study names the incentive. It does not specify a sandwich, a bundle format, or a current profit. Those details change, and copying them is not what this library is for.
Model
What has to hold
The measurements are about the exchanges and the period the paper studied. They are not a current volume figure.
Falsifier
What would retire it
What does the user allow: slippage, a deadline, or a revert?
03 Sequence
One action, as an operating tape
- 01A user broadcasts a DEX trade with a public slippage tolerance.
- 02Observers see it before it is mined.
- 03Searchers bid, by gas or by direct payment, to place their transactions around it.
- 04The block producer includes the winning order.
- 05The user's execution price is worse than the price they would have had without the insertion, by up to the slippage they allowed.
04 Load-bearing
The argument, and where a pitch drops it
MEV is a property of a transparent ordered log
The cut
Any chain that publishes intents and then lets one party order them creates the same shape of profit. Hiding the intent, constraining the order, or auctioning the right to order are different responses. The paper does not pick a product. It shows why doing nothing is a design.
Why it carries weight
If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.
Where it is dropped
This page does not describe how to front-run, sandwich, or auction order flow.
Private order flow does not delete the incentive
The cut
Later private mempools and builder auctions changed who sees the transaction and who gets paid. They did not make reordering worthless. A design that says MEV is solved has to say which of those actors still exists.
Why it carries weight
If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.
Where it is dropped
Private mempools and proposer-builder separation came later. They change who sees the order. They do not delete the incentive.
05 Register
What has to be true
Model · Not re-measured
The measurements are about the exchanges and the period the paper studied. They are not a current volume figure.
Model · Not re-measured
Users set slippage. A trade with zero slippage fails instead of being robbed. The loss moves from price to failure.
Model · Not re-measured
Block producers can order transactions. A protocol that removes that discretion removes this specific auction.
Model · Not re-measured
The DEX's price is a function of order. A constant-product pool is. An order book is too, with a different shape.
06 Divergence
What happened after the paper
The acronym MEV stuck. Searchers, builders, and proposer-builder separation grew up around the incentive the paper measured. None of that later market is in the 2019 data. The durable claim is the time-bandit: value that can be taken by reordering can become a bid for the chain itself. Cite the paper for that, not for a trading strategy.
A later client, parameter set, or reward formula is a different object. Cite this paper for the mechanism. Cite a primary release for the network. This desk has not re-run the proof.
07 Pre-mortem
What to check before you use the idea
- 0 of 4 marked on this browser. A mark is a reading note, not a pass, a rating, or a recommendation.
08 Anatomy
The paper, in the order a builder needs
The problem it names
Public mempools tell the world your trade before it is final. Whoever orders the block can trade ahead of it. The paper asks how large that effect already was on early Ethereum DEXs, and whether the extractable value can exceed the block reward.
What the design proposes
- Observe pending transactions and the gas auctions around DEX calls.
- Define extractable value as what a block producer can take by including, excluding, or reordering.
- A time-bandit incentive if stealing that value pays more than producing blocks honestly.
How the mechanism is specified
What this page does not treat as proven
- Figures from 2019 are not current market sizes. The mechanism is the part that aged into a category.
- This page does not describe how to front-run, sandwich, or auction order flow.
- Private mempools and proposer-builder separation came later. They change who sees the order. They do not delete the incentive.
Why the desk still reads it
Treat MEV as a property of a public ordered log, not as a product. A design that publishes intents before they execute has to say who is allowed to reorder them.
09 Lexicon
Terms, opened into the record
- Extractable value
- What a block producer can gain by including, excluding, or reordering transactions, beyond the protocol reward.
- Priority gas auction
- Searchers bidding in transaction fees to land in a specific position relative to a victim trade.
10 Repository
Every linked record on this page
Underlined words open a page that already exists: a concept, a protocol profile, a failure record, or another paper. If a word is not underlined, this desk does not have a record for it.
This is Blockchain Lab's reading of a public design paper. It is not the paper, not a copy of it, and not an offer of tokens, equity, custody or a partnership. Later network behaviour can diverge from the text. Nothing here is investment, legal or technical advice.
Research status: Design paper. Last reviewed: 1 October 2026. This is a reading of a public paper, not investment, legal or security advice.