The public mempool is the ephemeral ledger of pending transactions that determines who can observe and attempt on-chain arbitrage opportunities. Philip Daian Cornell Tech documented how visibility into pending transactions creates Miner Extractable Value that actors can capture by reordering, inserting, or censoring transactions. Mempool dynamics therefore turn raw price differentials into a battle over visibility and order rather than purely economic opportunity.
How mempool visibility shapes competition
When an arbitrage opportunity appears, its discoverability in the public mempool allows other bots and miners to react. Faster propagation and lower network latency give some nodes an edge, while aggressive gas bidding enables transactions to be prioritized by block producers. This combination produces a latency and fee arms race: multiple bots submit competing transactions with incrementally higher fees, increasing the probability of inclusion but lowering net profit. Public visibility also enables front-running and sandwich attacks that can steal or reduce the arbitrageur’s margin. Private transaction relays such as those promoted by Flashbots were developed to mitigate public mempool extraction by allowing bundles submitted directly to block producers, reducing wasteful fee competition but introducing concentration of power around relay operators and miners.
Consequences for arbitrageurs and markets
Success rates for on-chain arbitrage depend on three interlinked causes: transaction propagation timing, fee market dynamics, and block producer behavior. Faster submitters and those willing to pay larger fees succeed more often, while congested mempools increase transaction failure and slippage, eroding profit. When private pathways are used, guaranteed inclusion improves success predictability but centralizes leverage in a small set of relays and miners, with potential implications for fairness and censorship resistance. Territorial concentration of mining or validating infrastructure amplifies these effects because geographically advantaged operators can reduce latency for favored participants. Cultural factors within developer and operator communities influence whether open mempool practices are preserved or replaced by private routing, affecting access for smaller participants worldwide.
For practitioners, the trade-offs are clear: paying for speed, using private submission channels, or engineering lower-latency infrastructure raises success rates but incurs economic, centralization, and ethical costs. Policymakers and protocol designers must weigh these consequences for market integrity and for communities in regions with limited connectivity or market access.