--- name: prediction-markets-37bbbb80af3d description: >- Build tools and dashboards for prediction markets — Polymarket, Manifold, Kalshi, and Metaculus. Use when tasks involve fetching prediction market data, building probability dashboards, analyzing market liquidity, creating trading bots for prediction markets, visualizing event probabilities, or tracking forecasting accuracy. Covers both API integration and market analysis. license: Apache-2.0 compatibility: "No special requirements" metadata: author: terminal-skills version: "1.1.0" category: data-ai tags: "prediction-markets, polymarket, kalshi, forecasting, probability" --- # Prediction Markets ## Overview Build tools for prediction market platforms — fetch data, analyze markets, create dashboards, and implement trading strategies. Cover Polymarket, Kalshi, Manifold, and Metaculus APIs. ## Instructions ### Platform overview ``` Platform | Type | Markets | API | Trading -------------|-------------------|------------------|-----------|-------- Polymarket | Crypto (Polygon) | Binary/Multi | REST+WS | CLOB, wallet-signed orders Kalshi | Regulated (US) | Binary events | REST+WS+FIX | CLOB, API-key-signed orders Manifold | Play money (mana) | Any question | REST | AMM Metaculus | Forecasting | Probability est. | REST | No trading (API needs an account token) ``` ### Polymarket API Polymarket is the largest by volume. Reading market data needs no authentication. Three public hosts matter: Gamma (discovery and metadata), CLOB (prices, order books, history) and Data (positions, trades). Docs: https://docs.polymarket.com. Gamma returns `outcomes`, `outcomePrices` and `clobTokenIds` as JSON-encoded strings, so parse them. Price and book endpoints take the outcome **token ID** (from `clobTokenIds`), not the `conditionId`. ```python # polymarket_client.py import json import requests GAMMA_API = "https://gamma-api.polymarket.com" CLOB_API = "https://clob.polymarket.com" def get_active_events(limit: int = 100, offset: int = 0) -> list: """Fetch active events sorted by 24h volume (each has a `markets` list).""" resp = requests.get(f"{GAMMA_API}/events", params={ "limit": limit, "offset": offset, "active": "true", "closed": "false", "order": "volume24hr", "ascending": "false", }, timeout=15) resp.raise_for_status() return resp.json() def outcome_prices(market: dict) -> dict: """Map outcome label to price, e.g. {'Yes': 0.62, 'No': 0.38}.""" labels = json.loads(market["outcomes"]) prices = json.loads(market["outcomePrices"]) return {l: float(p) for l, p in zip(labels, prices)} def get_midpoint(token_id: str) -> float: r = requests.get(f"{CLOB_API}/midpoint", params={"token_id": token_id}, timeout=15) return float(r.json()["mid"]) def get_market_history(token_id: str, interval: str = "1d", fidelity: int = 60) -> list: """Price history for one outcome token: [{'t': unix_seconds, 'p': price}, ...].""" resp = requests.get(f"{CLOB_API}/prices-history", params={ "market": token_id, "interval": interval, "fidelity": fidelity}, timeout=15) return resp.json().get("history", []) ``` Other CLOB reads: `GET /book?token_id=...` (bids and asks), `GET /price?token_id=...&side=BUY`. Placing orders needs a funded wallet and the official unified SDKs (see the docs, "Place Your First Order"); never put a private key in code, read it from an environment variable. ### Market analysis ```python # market_analyzer.py import json def find_arbitrage_opportunities(markets: list, threshold: float = 0.02) -> list: """Find Gamma binary markets whose outcome prices don't sum to ~1.0.""" opportunities = [] for market in markets: if not market.get('outcomePrices'): continue prices = [float(p) for p in json.loads(market['outcomePrices'])] if len(prices) == 2: total = sum(prices) if abs(total - 1.0) > threshold: opportunities.append({ 'title': market['question'], 'deviation': abs(total - 1.0), 'volume_24h': market.get('volume24hr', 0) }) return sorted(opportunities, key=lambda x: x['deviation'], reverse=True) def calculate_expected_value(probability: float, buy_price: float, fees: float = 0.0) -> float: """EV per share. Set `fees` (fraction of price) from the venue's current fee schedule.""" cost = buy_price * (1 + fees) return probability * (1.0 - cost) - (1 - probability) * cost ``` ### Kalshi API Kalshi is CFTC-regulated (US-accessible). Docs: https://docs.kalshi.com. Market data is public; trading needs an API key pair (Ed25519 recommended, or RSA) created in account settings. The old email/password `/login` flow and the `trading-api.kalshi.com` host are gone (the old host now answers 401). Use `https://external-api.kalshi.com/trade-api/v2`; the demo environment `https://external-api.demo.kalshi.co/trade-api/v2` has separate keys. Prices are fixed-point dollar strings (`yes_bid_dollars: "0.4200"`) and quantities are `_fp` strings (`"13.00"`), not integer cents. The order book returns bids only (`orderbook_fp.yes_dollars` and `no_dollars`, each `[price, count]`): a YES bid at 0.42 is a NO ask at 0.58. ```python # kalshi_client.py import base64, os, time import requests from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey from cryptography.hazmat.primitives.serialization import load_pem_private_key BASE = "https://external-api.kalshi.com" PREFIX = "/trade-api/v2" def get_markets(series_ticker: str = "KXHIGHNY", status: str = "open") -> list: r = requests.get(f"{BASE}{PREFIX}/markets", params={"series_ticker": series_ticker, "status": status, "limit": 100}, timeout=15) return r.json()["markets"] # paginate with the returned `cursor` def get_orderbook(ticker: str) -> dict: r = requests.get(f"{BASE}{PREFIX}/markets/{ticker}/orderbook", timeout=15) return r.json()["orderbook_fp"] def signed_headers(method: str, path: str) -> dict: """Sign timestamp+METHOD+path (no query string). Ed25519 key; RSA keys use RSA-PSS/SHA-256.""" key = load_pem_private_key(open(os.environ["KALSHI_PRIVATE_KEY_FILE"], "rb").read(), password=None) ts = str(int(time.time() * 1000)) sig = key.sign((ts + method + path).encode()) # Ed25519 signs the message directly return {"KALSHI-ACCESS-KEY": os.environ["KALSHI_KEY_ID"], "KALSHI-ACCESS-TIMESTAMP": ts, "KALSHI-ACCESS-SIGNATURE": base64.b64encode(sig).decode()} def get_balance() -> dict: path = f"{PREFIX}/portfolio/balance" return requests.get(BASE + path, headers=signed_headers("GET", path), timeout=15).json() ``` Orders go to `POST /portfolio/events/orders` (Create Order V2: `ticker`, `side` of `bid`/`ask`, `count` and `price` as strings, `time_in_force`, `self_trade_prevention_type`). Try them on the demo host first. Official SDKs: `pip install kalshi_python_sync`, `npm install kalshi-typescript` (the old `kalshi-python` is deprecated); the OpenAPI spec at docs.kalshi.com/openapi.yaml is the source of truth. Each authenticated request spends tokens from a per-tier budget, see "Rate Limits and Tiers" in the docs. ### Manifold Markets API Play money (mana) — great for experimenting, no auth for reading (500 requests/minute/IP). Times are Unix milliseconds. `sort` accepts `score`, `liquidity`, `24-hour-vol`, `most-popular`, `newest`, `close-date` and others; `filter` accepts `open`, `closed`, `resolved`. The API is still marked alpha, and writes need an `Authorization: Key` header carrying your API key. ```python MANIFOLD_API = "https://api.manifold.markets/v0" def search_markets(query: str, limit: int = 20) -> list: return requests.get(f"{MANIFOLD_API}/search-markets", params={"term": query, "limit": limit, "sort": "liquidity", "filter": "open"}, timeout=15).json() ``` ### Dashboard building Key visualizations for a prediction market dashboard: 1. **Market cards**: Title, probability (color-coded), 24h volume, time to resolution 2. **Probability timeline**: Line chart showing momentum over time 3. **Volume bars**: 24h volume history showing market attention 4. **Alerts**: Markets where probability moved >10% in 24 hours ```python # market_scorer.py — Score markets for dashboard prominence def score_market(market: dict) -> float: score = 0.0 volume = float(market.get('volume24hr') or 0) prob = market.get('probability', 0.5) # from outcomePrices[0] or Manifold `probability` if volume > 100000: score += 30 elif volume > 10000: score += 20 elif volume > 1000: score += 10 uncertainty = 1 - abs(prob - 0.5) * 2 # 1.0 at 50%, 0.0 at extremes score += uncertainty * 25 prob_change = abs(market.get('probability_change_24h', 0)) if prob_change > 0.10: score += 20 elif prob_change > 0.05: score += 10 return min(score, 100) ``` ## Examples ### Build a prediction market dashboard ```prompt Build a real-time dashboard showing the top 50 Polymarket events sorted by 24-hour volume. Show each market as a card with: title, current probability (color-coded red-green), volume, time to resolution, and 7-day probability chart. Group by category (politics, crypto, sports, tech). Add alerts for markets where probability moved more than 10% in the last 24 hours. Use React and Chart.js. ``` ### Find mispriced prediction markets ```prompt Analyze all active Polymarket binary markets. Find markets where the Yes + No prices deviate more than 3% from $1.00 (indicating potential mispricing). Also find markets where the probability has been stable for weeks but a relevant news event just occurred. Output a ranked list of opportunities with expected value calculations. ``` ### Build a forecasting accuracy tracker ```prompt Build a system that tracks my prediction market bets across Polymarket and Kalshi, calculates my Brier score over time, and shows a calibration chart (predicted probabilities vs actual outcomes). Include position-size-weighted returns and compare my accuracy against the market's consensus probabilities. ``` ## Guidelines - Always check market liquidity (24h volume) before placing trades — low-liquidity markets have wide spreads - In binary markets, verify Yes + No prices sum to ~$1.00; small deviations are normal spread, not free money - Use Manifold (play money) for strategy testing before deploying capital on Polymarket or Kalshi - Compare your forecasts against market consensus to measure calibration over time - Monitor for >10% probability swings in 24 hours — these often signal new information or mispricing - Be aware that Polymarket is crypto-based (Polygon) while Kalshi is CFTC-regulated with different rules, fees and access restrictions by country; check current eligibility and fee schedules before trading - Calculate expected value before every trade; don't trade based on conviction alone --- Source attribution: terminal-skills Original project: https://github.com/TerminalSkills/skills/blob/8a9852d489f274538be9bf1c9121aeb403750b1c/skills/prediction-markets/SKILL.md License: Apache-2.0 License information: https://www.apache.org/licenses/LICENSE-2.0 Original upstream instructions; downloaded from Dave AI. ## Upstream license notice Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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See the License for the specific language governing permissions and limitations under the License. # Dave AI resource metadata Creator / publisher: terminal-skills Original project: https://github.com/TerminalSkills/skills/blob/8a9852d489f274538be9bf1c9121aeb403750b1c/skills/prediction-markets/SKILL.md Attribution basis: Source repository record Fields of work: Data & Analytics, Development & Engineering, Marketing, Product Management Roles: Data Analyst, ML / AI Engineer, Growth Marketer, Product Manager, Market Research Analyst Specialties: API Tools: Polymarket, Kalshi, Metaculus, Manifold Country applicability: United States Classification basis: Source category, role and specialization labels Instruction SHA-256: 51c717ffed793d37e728273100f92fd1be4281eb26f33330f65a335adfa49fd3