St. Louis Cardinals vs. Cincinnati Reds

Platform comparison

Market context

The St. Louis Cardinals are pricing at about 72% to win, which implies a solid favourite on Polymarket rather than a lock. The contract settles in USDC on Polygon through conditional tokens, so the market is effectively weighing the Cardinals’ win probability against a Reds home upset, with no payout until the official result is final.

Recent form supports that lean, but not overwhelmingly. St. Louis split the first two games of the set in Cincinnati on 17 August, winning 2-1 before losing 6-5 in the nightcap, leaving the Cardinals 64-62 and the Reds 60-65 in the latest standings. The Cardinals also carry a better run differential and a stronger overall record, while Cincinnati remains below .500 and has struggled to turn home games into wins.

For traders, the main catalysts are lineup confirmation, any pitching change, and whether the scheduled start remains intact. MLB’s game preview lists the fixture for 18 August at 6:40pm ET, and any late scratch or bullpen-heavy adjustment would matter more than the title race context. If the game is postponed, the market stays open until completion; if it is cancelled without a make-up or ends level, the contract resolves 50-50.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

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 PolyGram. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

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.