Historical order books and trades for every sports market Polymarket runs — MLB, ATP, ITF, the football and basketball books, and the one-off finals and futures.
Sports books reprice against a known event clock, which makes them the cleanest natural experiment on the venue: the same market, repeatedly, with a scheduled information release in the middle. The live game-state feed that these markets move against is sold alongside as its own dataset.
A free account claims 5 market·days from July 2026, or buy a single market·day à la carte from $2.
Ranked by how many distinct questions each one has run. Every title links to its own coverage page.
The same three layers as everywhere else in the archive: L1 best bid/ask written on every change, the 25-level L2 ladder on every book update, and the complete trade tape with price, size and aggressor side. All of it came off Polymarket's own websocket feed as it happened, recorded by dual-region sequence-audited collectors — not reconstructed from a public REST endpoint afterwards, which is the difference that matters once you care about resting size and spread regimes.
Bundles arrive as parquet with a CSV twin and a reference dictionary mapping every id back to the real question. The full schema is documented here.
For the archive as a whole rather than the sports slice, see Polymarket historical data.