St. Louis Cardinals vs. Arizona Diamondbacks

Platform comparison

Market context

The Arizona Diamondbacks defeated the St. Louis Cardinals 8–7 in a dramatic 10th-inning walk-off at Chase Field on 19 July 2026, with Max Kepler hitting the decisive RBI double after rallying from a seven-run deficit [1][3]. This result confirms the game has already concluded, rendering the prediction market’s 0% YES probability for a Cardinals win factually accurate and settled in favour of the Diamondbacks [2].

Historically, prediction markets with 0% implied probability on a team that has already lost reflect immediate resolution rather than speculative divergence; similar cases in MLB, such as the 2023 Houston Astros’ walk-off losses, saw odds collapse to zero within minutes of the final play, with no subsequent line movement across sportsbooks [3]. Here, the sportsbook moneyline of –126 for Arizona and +108 for St. Louis aligns precisely with the outcome, showing no meaningful gap between bookmaker lines and the market’s settled state [2][5].

Traders should note that settlement is now moot, as the official final statistics confirm the Diamondbacks’ victory and the market will resolve to “Arizona Diamondbacks” without further dependency [3]. No announcements, schedule changes, or pitcher dependencies apply, given the game’s completion; the only remaining action is administrative closure of the contract by the platform [4].

Sources: 1 · 2 · 3 · 4 · 5

Methodology

We track St. Louis Cardinals vs. Arizona Diamondbacks across the five venues with material prediction-market liquidity. The probability shown is the live Polymarket mid; the comparison rows summarise how each venue treats the underlying contract — fees, KYC thresholds, settlement currency, deposit options. The highlighted row marks the cheapest route into Polymarket's order book.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

Polymarket is geo-blocked in the US/UK/EU. The easiest 0%-fee broker into the same order book is Best Prediction Markets UK. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

What's the difference between YES and NO shares?

A YES share pays $1.00 if the event happens, $0 otherwise. A NO share pays $1.00 if the event doesn't happen. The market price between 0¢ and 100¢ is the implied probability.

What does Polymarket cost to trade?

Polymarket itself charges 0% — the only cost is the Polygon network fee, typically under $0.01 per transaction. Off-chain venues like Kalshi or Betfair charge 2-7% commission.

Do I need to KYC for this market?

On Polymarket directly, no — it's wallet-based. Intermediary brokers like Best Prediction Markets UK trigger KYC only above $1,500 of lifetime trading volume; under that you trade pseudonymously with a single wallet address.