San Francisco Giants vs. Seattle Mariners

Platform comparison

Market context

The San Francisco Giants and Seattle Mariners face off in a scheduled MLB game on 19 July at 4:10PM ET, with the market currently pricing a Giants win at 0% probability despite their dominant 7-0 victory over Seattle just two days prior in the first post-All-Star break contest. This stark divergence suggests the crowd is either reacting to a specific, unpublicised roster change or misinterpreting the settlement window, which extends to 26 July 2026, potentially conflating this single game with a broader series outcome or a future matchup where the Giants are indeed disadvantaged.

Historical head-to-head data shows the Giants have swept a three-game series against Seattle in April 2025 and won the most recent encounter decisively, making the current 0% implied probability an outlier that contradicts recent performance trends unless a critical injury or lineup alteration has occurred overnight. Programmatic traders should treat this as a potential arbitrage opportunity, deploying conditional orders to buy YES on the Giants if the price remains depressed while monitoring official MLB injury reports for any late announcements regarding key hitters like Bryce Eldridge or pitcher Landen Roupp.

Traders must watch for real-time updates on the starting rotation and any postponement notices, as the market remains open until the game is completed if delayed, with a 50-50 resolution only if the match is cancelled entirely or ends in a tie. A recent game overview confirms the Mariners secured a narrow 4-3 win in a previous 10th-inning thriller, indicating the series is competitive, but the Giants’ recent 7-0 shutout suggests the current pricing may be a technical error rather than a reflection of genuine team weakness.

Sources: 1 · 2 · 3

Methodology

We track San Francisco Giants vs. Seattle Mariners 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

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.

How reliable are the quoted odds?

The YES/NO percentages are the live mid-prices of the Polymarket order book. On deep markets they move every few seconds; on thinner ones you'll see short plateaus.