Prediction Market Settlements & Terms API — Kalshi + Nadex Ground Truth

Know what your prediction-market contract ACTUALLY settles on before you trade it.

Every other prediction-market actor on the Apify Store sells you prices. This one sells ground truth: official settlement values, contract settlement rules, and a venue-aware settlement-reference classifier that tells you whether hedging a binary with options is a clean pair or a basis trade that can lose both legs.

Why this exists

Prediction markets with near-identical titles settle on different underlyings:

Market	Looks like	Actually settles on
Kalshi KXINXU "S&P 500 above X at 4pm"	SPX	SPX cash index (close auction) ✅ hedgeable with SPX options
Coinbase Predict "S&P 500 above X"	SPX	ES futures on most listings ⚠️
Nadex "US 500 >7707 (4:15PM)"	SPX	ES futures ⚠️
Crypto.com Predict S&P	SPX	ES futures at 4:15pm (15 min after cash close) ⚠️
Robinhood event contracts S&P	SPX	ES futures ⚠️

Pairing a futures-settled binary with cash-settled options is a basis trade, not an arb — when cash < strike < futures, you lose both legs. Real traders have lost real money this way. This actor is the pre-trade check.

Modes

1. classify — settlement-reference check (the killer feature)

Input any market title/slug + venue → settlement reference, detail, and hedging verdict.

{ "mode": "classify",
  "items": [
    {"venue": "coinbase", "title": "S&P 500 or above 7,700 at 4pm ET"},
    {"venue": "kalshi",   "title": "KXINXU-26SEP30H1600 S&P 500 above/below"}
  ] }

→ CHECK_SLUG — MUST verify slug before pairing with options / SPX_CASH — CLEAN pair with SPX/XSP cash-settled options

Covers: Kalshi, Coinbase Predict, Nadex, Crypto.com, Robinhood, generic S&P/Nasdaq fallbacks.

2. terms — Kalshi contract terms (live, keyless)

{ "mode": "terms", "tickers": ["KXINXU-26SEP29H1600-T7869.9999"] }

Returns: full rules_primary settlement text, result, close_time, expiration_value (the actual settlement print), custom_strike, plus settlement-ref classification.

3. settlements — settled outcomes

• Kalshi (live API): settled markets in a date window, with results and settlement values. { "mode": "settlements", "venue": "kalshi", "series": "KXINXU", "date_from": "2026-09-01", "date_to": "2026-09-30" }
• Nadex (official daily Trading Results PDFs, parsed & cached): every contract's expiration time + expiration value + winner side, pre-classified by product (US 500→ES futures, US TECH 100→NQ, CRUDE→CL, GOLD→GC...). { "mode": "settlements", "venue": "nadex", "dates": ["20260929"] }

4. refresh_cache — keep Nadex data current

Parses the last N days of official Nadex PDFs into the actor KV store. Run this on an Apify Schedule (daily, 22:00 UTC).

Pricing (pay-per-event)

• terms lookup: $0.01/market
• settlements row: $0.005/row
• classify run: $0.01/run (up to 200 items)
• refresh_cache: free (internal)

Data provenance & legality

• Kalshi: public keyless trade API (GET only) + each market's own rules_primary text.
• Nadex: official daily Trading Results PDFs published by the exchange at a public S3 bucket — the exchange's own settlement record.
• This actor does not resell live order books or any venue's proprietary market data; it redistributes published settlement records and contract terms.

Use cases

• Pre-trade settlement check for prediction-market/options arb
• Backtest ground truth: score your PM signals against actual settlements
• Build venue settlement-reference tables without getting burned
• Academic research on prediction-market settlement mechanics