Seattle Mariners vs. Kansas City Royals

Platform comparison

Active sub-markets

Market context

The Seattle Mariners and Kansas City Royals meet in a one-game MLB market that is close to a coin flip, with the crowd at 52% for Seattle. That level is broadly consistent with the teams’ recent head-to-head profile: Kansas City beat Seattle 3-2 in extra innings on 2 May, a reminder that these match-ups can stay tight and turn on late bullpen execution rather than a single dominant starter. In markets priced around this range, the key issue is usually whether one side has a clear starting-pitching or matchup edge that moves the game away from a one-run contest.

The immediate catalyst is the game itself rather than any longer-dated schedule or roster event, so traders will be watching the confirmed starters, line-ups and any late scratches as the clearest drivers of movement. Seattle’s probability should be tested if the Mariners can field their preferred order against Kansas City’s starting arm, while the Royals gain value if they can keep the game in the sort of low-scoring, one-run range that showed up in the earlier meeting. Recent previews and recaps from ESPN and MLB point to a recurring pattern of modest run totals and narrow margins, which means late bullpen usage and extra-innings risk remain relevant right up to first pitch.

Sources: 1 · 2 · 3 · 4 · 5

Methodology

This page tracks Seattle Mariners vs. Kansas City Royals across four political prediction venues. Live odds come from the Polymarket order book (the deepest political prediction-market book). Kalshi is the CFTC-regulated US alternative, Betfair the established UK sports-exchange with politics markets, Manifold the open play-money variant. PolyGram routes every trade through to Polymarket — at 0% fees.

Resolution & payout

Political markets typically settle on official candidate or agency confirmation. Polymarket uses UMA Optimistic Oracle: a proposer posts the outcome with a bond, the two-hour window opens, then the smart contract pays USDC.

Kalshi settles USD via CFTC clearinghouse, with clearly defined resolution sources (e.g. AP race calls for elections). Betfair settles after the official outcome is registered with the league or agency. Manifold is play-money.

FAQ

Where can I trade this market with the lowest fees?

On PolyGram, 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.

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 it cost to trade on PolyGram?

Zero. PolyGram routes every order to the live Polymarket order book; the only cost is the Polygon network fee, typically under $0.01 per transaction.

Do I need to KYC for this market?

Not under $1,500 of lifetime trading volume. Above that threshold, PolyGram triggers a quick verification flow that finishes in 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.