Two Crowds — does Polymarket or the options market see the close better?

TL;DR · On 1,352 resolved Polymarket stock questions, the probability implied by options (from Unusual Whales implied volatility) forecast slightly better than Polymarket's own price. When the two disagreed by 10+ points, options were closer 64% of the time, and taking the options side on Polymarket returned about +25% per $1.

Open the live site · Watch the 80-second demo · MCP endpoint https://two-crowds.onrender.com/mcp-server/mcp

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1 · The question

Every trading day Polymarket lists ladders like "Will NVIDIA (NVDA) close above $210 on October 23?" and "Micron (MU) Up or Down on October 23?". Thousands of people bet on them.

The options market prices the very same events: a stock closing above a level by a date is exactly what calls pay out on. It just never prints the answer as a percentage. Two Crowds does, and then asks which crowd was closer.

2 · The method

Both forecasts at the same instant. For each market we take 4pm New York on the trading day before it resolves:

"Up or Down" questions use the prior close as K. Earnings-beat questions can't be priced from options, so they are shown next to the options flow instead of being scored.

Scoring. Each forecast gets a Brier score (0 is perfect, 0.25 is a coin flip). The trading test was fixed before the first run: when the crowds split by 10+ points, stake $1 on the options crowd's side at Polymarket's price plus 1¢.

3 · The result

Taking the options side: +25% per $1 over 170 trades, 64% won. Resampling whole days (strikes on one day move together), the 95% range is +4% to +45%. It survives only using markets that traded in the last hour before the close (1,300 of 1,352), and a 2–3¢ cost.

Read it carefully: the average leans on a few big wins (without the top 10 it is +2.5%, the median trade is still about +24%); 26 days is short; Polymarket fees and fill size are ignored; σ is at the money, so far strikes carry skew the model leaves out.

4 · Try it

MCP tools (read-only): two_crowds_today · two_crowds_track_record · implied_probability · two_crowds_market, plus the prompt where_do_the_crowds_disagree. skill/SKILL.md is a Claude skill that pairs them with the Unusual Whales MCP server for live flow and prediction-market data.

5 · What Unusual Whales adds

• Unusual Predictions: /api/predictions/unusual (unusual score, smart-money volume, possible insider wallets, tags) with /api/predictions/smart-money, /api/predictions/insiders, /api/predictions/market/{asset_id}

• The options view: /api/stock/{t}/interpolated-iv (today and past dates), /api/stock/{t}/ohlc/1d

• Which way big bets lean: /api/option-trades/flow-alerts, counting only premium bought at the ask

• Live context in Claude: the Unusual Whales MCP server

Run it yourself

python3 -m venv .venv && .venv/bin/pip install -r requirements.txt
cp .env.example .env                         # UW_API_KEY=… or leave empty for the saved run
.venv/bin/python -m twocrowds.cli backtest   # rebuild the track record (cached, safe to rerun)
.venv/bin/python -m twocrowds.cli serve      # http://127.0.0.1:8040

today, record, export-demo and mcp (stdio) are the other commands; .venv/bin/python -m pytest runs the tests. To host: any Docker host. On Render, New → Blueprint reads render.yaml; set UW_API_KEY and PUBLIC_HOSTS (the app's host name, so the MCP endpoint accepts it). Pages never wait on the APIs: the live board refreshes in the background and the saved run fills in until it's ready.

FAQ

Why not just use the options' delta? Delta is close to N(d1), not the probability of finishing above the strike; N(d2) is the risk-neutral probability itself.

Isn't this one-sided? Both crowds are scored identically, at the same moment, on the same outcomes. If Polymarket had been closer, the scoreboard would say so.

Is it a trading signal? It's a research tool with a short record. Treat the +25% as a reason to keep watching, not to bet.

Code under the MIT license. Data belongs to its providers: Unusual Whales under your own key and its terms, Polymarket through its public API. Not financial advice.