Boston Red Sox vs. Seattle Mariners

Platform comparison

Active sub-markets

Market context

The Boston Red Sox face the Seattle Mariners in a crucial MLB game scheduled for June 20 at 10:10PM ET, with the crowd-implied probability currently favouring the Red Sox at 47% YES. On Polymarket, this contract trades on the Polygon network using USDC, where conditional tokens reflect the on-chain mechanics of the settlement window ending in late June 2026. The price today suggests a tight contest, with the market pricing the Red Sox as slightly less likely to win than the Mariners, despite the Red Sox's recent form.

Historically, similar MLB matchups between these franchises have shown volatile outcomes, with the Mariners often overcoming lower probabilities in away games. For instance, in the June 19, 2026 game, the Mariners won 6-2, demonstrating their capacity to defy odds[3]. This pattern frames the current 47% probability as a cautious assessment, where the Red Sox's advantage is not as definitive as the odds might imply, given the Mariners' resilience in comparable scenarios.

Traders should monitor the starting lineups and any injury announcements before the game, as these catalysts can shift probabilities significantly. Recent news from FanDuel indicates the Mariners are favoured to win their next game at -130 odds, suggesting strong momentum[1]. Additionally, the settlement window's dependency on official final statistics means any postponement or cancellation could keep the market open, requiring traders to watch for updates on the game schedule closely.

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). The odds column is filled only where we have clean data — that avoids the made-up numbers that get a network demoted when search engines cross-check against the source venue.

Resolution & payout

At resolution the UMA oracle takes over: a proposer posts the outcome with a bond, any token holder can dispute within two hours. Without dispute the result is accepted and the smart contract distributes USDC instantly.

On Kalshi (CFTC-regulated) resolution runs through their in-house clearing engine in USD. Betfair Exchange settles after match end in the account's local currency. Manifold pays no cash — only its in-platform "mana" currency.

FAQ

Where can I trade this market with the lowest fees?

On Polymarket Legit?, which mirrors the Polymarket order book at 0% fees. 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.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

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.