Advanced

How good the prices are and where the depth sits — price accuracy by category, order-book liquidity across venues, and whether traders come back.

Accuracy

How good the prices are — direction-match and Brier calibration by category, and where the two venues disagree.

Price Accuracy by Category

Direction-match %, implied price 24h before close — sharpest category first

SNAPSHOT

Methodology → Case study · Accuracy →

Get this dataCopy a runnable request for the data behind this view.View requestHide request

curl -s "https://api.asksurf.ai/gateway/v1/prediction-market/report-chart?id=accuracy-by-category" -H "Authorization: Bearer $SURF_API_KEY"

Live-verified 2026-07-07: currently serves the committed snapshot (minN 200, Poly 128K / Kalshi 1.1M resolved outcomes, May 1-Jun 30) while the report-chart backend ships — same envelope this panel reads via usePrecompute.

PolymarketKalshi

Liquidity

How order-book depth is split across venues for the markets that trade on both.

Venue liquidity share

Loading matched pairs…

SNAPSHOT

PolymarketKalshi

See the matching daily endpoint →

Get this dataCopy a runnable request for the data behind this view.View requestHide request

curl -s "https://api.asksurf.ai/gateway/v1/prediction-market/matching/pairs?limit=100" \
  -H "Authorization: Bearer $SURF_API_KEY"

curl -s "https://api.asksurf.ai/gateway/v1/prediction-market/matching/daily?polymarket_condition_id=$CID&kalshi_market_ticker=$TICKER&time_range=90d" \
  -H "Authorization: Bearer $SURF_API_KEY"

Captured 2026-07-09. matching/pairs returns the cross-venue mapping (Polymarket condition_id <-> Kalshi ticker); $CID/$TICKER are a matched row's polymarket.condition_id / kalshi.market_ticker — e.g. Fed-no-cuts: 0xd4e77ba6f29fc093509d24f508631abd445ecf506bbdc9c4c80e60256a318527 / KXRATECUTCOUNT-26DEC31-T0. matching/daily returns each venue's daily volume for that pair; liquidity share = each venue's share of daily traded notional (Polymarket notional_volume_usd in USD; Kalshi daily contract volume valued at a $1-per-contract proxy), 7-day trailing-smoothed — the ratio between venues, not the dollar level, is the signal. The two venues price the same event within ~2¢ yet can split the flow very differently, and that split shifts across the 90-day window.

Retention

Do traders come back? Polymarket wallets grouped by the month of their first-ever trade, then tracked month by month. Polymarket only — Kalshi publishes no trader identity.

Wallet Retention

Share of each first-trade cohort still trading months later · monthly cohorts · Polymarket

SNAPSHOT

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