> ## Documentation Index > Fetch the complete documentation index at: https://docs.openpx.trade/llms.txt > Use this file to discover all available pages before exploring further. # Market mapping > How each upstream exchange schema maps to OpenPX Market. *A prediction market on the unified surface. Prices are YES probabilities in `[0, 1]`.* Every field is one of three entry types — **direct** (taken from upstream), **synthetic** (computed by OpenPX), or **omitted** (not exposed upstream). ## Coverage | Exchange | Direct | Synthetic | Omitted | | ---------- | ------ | --------- | ------- | | kalshi | 13 | 8 | 4 | | polymarket | 18 | 7 | 0 | ## Field crosswalk | Unified field | Type | kalshi source | polymarket source | Notes | | -------------------- | ------------------- | --------------------------- | ------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `openpx_id` | string | *synthetic* | *synthetic* | **kalshi:** Composite key `\{exchange\}:\{ticker\}`. **polymarket:** Composite key `\{exchange\}:\{ticker\}`. | | `exchange` | string | *synthetic* | *synthetic* | **kalshi:** Literal string `"kalshi"`. **polymarket:** Literal string `"polymarket"`. | | `ticker` | string | `Market.ticker` | `Market.slug` | **kalshi:** Native Kalshi market ticker. **polymarket:** Polymarket slug; stable, human-readable identifier (numeric id lives in `numeric_id`). | | `numeric_id` | string? | *omitted* | `Market.id` | **kalshi:** Kalshi has no separate numeric id surface. **polymarket:** Polymarket numeric DB id used for REST deep-links. | | `event_ticker` | string? | `Market.event_ticker` | *synthetic* | **kalshi:** Native Kalshi event ticker. **polymarket:** Read from the embedded `events[0].slug` (falls back to `events[0].id`). | | `title` | string | *synthetic* | `Market.question` | **kalshi:** Composed as `\{yes_sub_title\} \| \{no_sub_title\}`. **polymarket:** Polymarket market question text. | | `rules` | string? | *synthetic* | `Market.description` | **kalshi:** Composed as `\{rules_primary\} \| \{rules_secondary\}`. **polymarket:** Polymarket market description. | | `status` | MarketStatus | *synthetic* | *synthetic* | **kalshi:** Mapped from Kalshi's `status` enum (initialized/active/closed/determined/...) to unified `MarketStatus`. **polymarket:** Combined from the `active`/`closed`/`archived` booleans into unified `MarketStatus`. | | `market_type` | MarketType | *synthetic* | *synthetic* | **kalshi:** Mapped from Kalshi's `market_type` enum (binary/scalar) to unified `MarketType`. **polymarket:** Derived from `outcomes.len()` — binary if 2, otherwise categorical. | | `outcomes` | array | *synthetic* | *synthetic* | **kalshi:** Two entries (`Yes`/`No`); price computed from `yes_ask_dollars`/`last_price_dollars`. **polymarket:** Zipped element-wise from the stringified-JSON arrays `outcomes`, `outcomePrices`, `clobTokenIds`. | | `condition_id` | string? | *omitted* | `Market.conditionId` | **kalshi:** Kalshi has no CTF condition id. **polymarket:** On-chain CTF condition id. | | `volume` | number (double) | `Market.volume_fp` | `Market.volumeNum` | **kalshi:** FixedPointCount string parsed to f64 USD. **polymarket:** Lifetime volume in USD. | | `volume_24h` | number? (double) | `Market.volume_24h_fp` | `Market.volume24hr` | **kalshi:** FixedPointCount string parsed to f64 USD. **polymarket:** 24-hour volume in USD. | | `last_trade_price` | number? (double) | `Market.last_price_dollars` | `Market.lastTradePrice` | **kalshi:** Fixed-point dollar string parsed to YES probability in \[0, 1]. **polymarket:** Already a YES probability in \[0, 1]. | | `best_bid` | number? (double) | `Market.yes_bid_dollars` | `Market.bestBid` | **kalshi:** Fixed-point dollar string parsed to YES probability in \[0, 1]. **polymarket:** Already a YES probability in \[0, 1]. | | `best_ask` | number? (double) | `Market.yes_ask_dollars` | `Market.bestAsk` | **kalshi:** Fixed-point dollar string parsed to YES probability in \[0, 1]. **polymarket:** Already a YES probability in \[0, 1]. | | `tick_size` | number? (double) | `Market.price_ranges` | `Market.orderPriceMinTickSize` | **kalshi:** Smallest `step` across all tiers in the `price_ranges` array. **polymarket:** Single scalar tick size. | | `min_order_size` | number? (double) | *synthetic* | `Market.orderMinSize` | **kalshi:** 1.0 by default, 0.01 when `fractional_trading_enabled`. **polymarket:** Polymarket minimum order size in contracts. | | `open_time` | string? (date-time) | `Market.open_time` | `Market.startDate` | **kalshi:** RFC3339 string parsed to UTC. **polymarket:** ISO 8601 string parsed to UTC. | | `close_time` | string? (date-time) | `Market.close_time` | `Market.endDate` | **kalshi:** RFC3339 string parsed to UTC. **polymarket:** ISO 8601 string parsed to UTC. | | `created_at` | string? (date-time) | `Market.created_time` | `Market.createdAt` | **kalshi:** RFC3339 string parsed to UTC. **polymarket:** ISO 8601 string parsed to UTC. | | `settlement_time` | string? (date-time) | `Market.settlement_ts` | `Market.closedTime` | **kalshi:** RFC3339 string parsed to UTC. **polymarket:** On-chain settlement time, populated only after the market resolves. | | `neg_risk` | boolean? | *omitted* | `negRisk` *(spec gap)* | **kalshi:** Kalshi has no neg-risk concept. **polymarket:** Spec gap: `negRisk` is present on every live `/markets` row but undeclared on `Market` in the gamma OpenAPI. | | `neg_risk_market_id` | string? | *omitted* | `negRiskMarketID` *(spec gap)* | **kalshi:** Kalshi has no neg-risk concept. **polymarket:** Spec gap: present on every live `/markets` row but undeclared on `Market` in the gamma OpenAPI. | | `result` | string? | `Market.result` | *synthetic* | **kalshi:** Native Kalshi resolution enum string. **polymarket:** Winning `outcomes[i]` where `outcomePrices[i] == 1.0` after settlement. | ## Source specs * **kalshi** · [`schema/upstream/kalshi.openapi.yaml`](https://github.com/openpx-trade/openpx/blob/main/schema/upstream/kalshi.openapi.yaml) * **polymarket** · [`schema/upstream/polymarket-gamma.openapi.yaml`](https://github.com/openpx-trade/openpx/blob/main/schema/upstream/polymarket-gamma.openapi.yaml) > Tables are auto-generated from `schema/mappings/`. CI fails if any `direct` ref no longer resolves in the cached upstream spec; the daily upstream-refresh PR surfaces drift here.