Arbitrage#055

Betfair Lay vs. Polymarket Back Cross-Venue Lock

Some sports and politics events appear on both Betfair Exchange and Polymarket. You bet on the outcome at whichever venue is cheaper and bet against the same outcome on the other (on Betfair this is called 'laying'), after converting Betfair's decimal odds into a probability so the two prices are comparable. Holding both to the result locks in the spread. The edge is the price gap between a traditional exchange and an on-chain order book whose audiences and reaction speeds differ.

What you need to run it

Betfair Exchange API + Polymarket feed with odds normalization
Event/outcome matching incl. resolution-rule parity check
Bankroll on both venues with commission accounting
Fast re-quote to avoid one-legged exposure

Where this applies

Markets on Polymarket where betfair lay vs. polymarket back cross-venue lock is the natural play:

Will Manchester City win the 2026-27 Premier League title?
Will Jon Jones win his next UFC title fight?
Will Labour win the next UK general election?

Capabilities this demands

Multi-venueFeed ingestionSignificant capitalLow latency

At a glance

CategoryArbitrage

Requirements4

CapabilitiesMulti-venue, Feed ingestion, Significant capital, Low latency

VenuePolymarket (CLOB, Polygon)

Build it

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This is documentation, not advice. Poly Research & Robotics publishes how these strategies work because the method should be checkable — not as a recommendation to trade them. See the full strategy database (147 strategies) or the data resources directory.