The Prediction Markets

Pro Baseball Champion

Closes
Oct 31, 2028, in 25 months
Traded
$179.2M
Venues
Polymarket, Kalshi
Prices updated
just now
Share

What the markets expect

Milwaukee 63.9%

Next is Tampa Bay at 36.1%. The venues differ most on Milwaukee (Polymarket 63.2%, Kalshi 64.8%), a 1.7-point gap.

Milwaukee 63.9%Tampa Bay 36.1%

Odds by venue

Fair chance strips out each venue’s built-in margin (its prices add up to more than 100%), then blends the venues by how much has traded there, so the outcomes add up to 100%. Best Yes price is the cheapest ask across venues, and the payout is what a winning $100 stake returns before fees. Open a row for each venue’s contract name, bid and ask, and how closely their rules match.

2 of 4 prices are live from the exchange feeds; the rest come from our regular price polls, the oldest 1 min ago. Ages are as of when this page was built.

  • Polymarket
  • Kalshi
MilwaukeeArb
63.9%
Polymarket 63.2%live, just nowKalshi 64.8%(64.2% fair)live, just nowBest Yes 63.2¢ on Polymarket, $100 pays $158 (1.58x)
Polymarket
Contract
Milwaukee Brewers
Price
63.2%
As of
Live feed, just now
Buy Yes
63.2¢
Sell Yes
63.1¢
$100 on Yes pays
$158 (1.58x)
Volume
$2.1M
Trade this on Polymarket
Kalshi
Contract
Milwaukee
Price
64.8%
Fair, margin removed
64.2%
As of
Live feed, just now
Buy Yes
64.8¢
Sell Yes
64¢
$100 on Yes pays
$154 (1.54x)
Volume
$11.4M
Trade this on Kalshi
Partial parity

Payoffs match in ordinary outcomes; see the rule differences below the table.

Buying on Polymarket at 63.2¢ and selling on Kalshi at 64¢ nets 80 bps before fees.

Tampa BayArb
36.1%
Polymarket 37%polled, 1 min agoKalshi 36.2%polled, 1 min agoBest Yes 36.2¢ on Kalshi, $100 pays $276 (2.76x)
Polymarket
Contract
Tampa Bay Rays
Last price
37%
As of
Polled 1 min ago
Buy Yes
37.1¢
Sell Yes
36.9¢
$100 on Yes pays
$270 (2.70x)
Volume
$980K
Trade this on Polymarket
Kalshi
Contract
Tampa Bay
Last price
36.2%
As of
Polled 1 min ago
Buy Yes
36.2¢
Sell Yes
35.6¢
$100 on Yes pays
$276 (2.76x)
Volume
$7.4M
Trade this on Kalshi
Partial parity

Payoffs match in ordinary outcomes; see the rule differences below the table.

Buying on Kalshi at 36.2¢ and selling on Polymarket at 36.9¢ nets 70 bps before fees.

Possible arbitrage before fees: buy Milwaukee on Polymarket at 63.2¢, sell on Kalshi at 64¢ (80 bps). Check the rules below before trading. See all live spreads

Mostly the same bet: 3 differences

Where they differ

  • Both settle on the official league/organizer result for the named season; Kalshi's season is the ticker edition (KXNBA-27 = 2026-27) and Polymarket's is stated in the title or slug.
  • Season cancelled or not completed: Kalshi resolves per its rules (typically a fair price); Polymarket resolves to 'Other' or 50-50 depending on the event.
  • Polymarket lists placeholders ('Other', 'Team A') and closes eliminated outcomes early; only live named outcomes are linked.
Polymarket
Polymarket resolves via:
UMA optimistic oracle, source: mlb.com
Kalshi
Kalshi resolves via:
Kalshi (CFTC-regulated exchange), source: AP, Fox Sports, ESPN
Show full rule comparison
  • Both settle on the official league/organizer result for the named season; Kalshi's season is the ticker edition (KXNBA-27 = 2026-27) and Polymarket's is stated in the title or slug.
  • Season cancelled or not completed: Kalshi resolves per its rules (typically a fair price); Polymarket resolves to 'Other' or 50-50 depending on the event.
  • Polymarket lists placeholders ('Other', 'Team A') and closes eliminated outcomes early; only live named outcomes are linked.
  • Trading closes Oct 31, 2026, 11:55 PM UTC on Polymarket and Oct 31, 2028, 4:00 AM UTC on Kalshi.

Summarized from each venue’s published rules; the venue’s own rules page is the final word.

How the odds have moved

The top 2 outcomes on both venues, with the consensus between them. Hover for exact values.

  • Milwaukee
  • Tampa Bay

Live prices for Milwaukee

What it costs to buy Yes, what you would get selling it, and the last trade on each exchange, updating as orders change. Hover a status for timing details.

Order books

Each venue’s resting orders for the selected outcome’s Yes contract, side by side. Top of book streams live; depth refreshes every 15 seconds.

Combined depth · both venues

Loading both order books…

Polymarket

Open on Polymarket ↗

Top of book

Connecting
Best bid
—
Spread
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Best ask
—

Waiting for the first live quote…

Depth · top 8 levels

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Recent trades

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Kalshi

Open on Kalshi ↗

Top of book

Connecting
Best bid
—
Spread
—
Best ask
—

Waiting for the first live quote…

Depth · top 8 levels

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Recent trades

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What your stake buys

Enter a stake to see where it buys the most after fees, using each venue’s live order book.

$
Buy

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Cover all 2 outcomes across venues

Loading every outcome’s book…

Buys at the asks resting now (taker orders), cheapest after fees first, from order-book snapshots up to 15 seconds old. Fees: Kalshi 0.07 × price × (1 − price) per share, rounded up to the cent; Polymarket 0.05 × price × (1 − price) per share (sports rate). Fee calculator. Estimates only, not advice.

About this market

Live prediction market odds for "Pro Baseball Champion". Milwaukee leads at 63.9%. Next is Tampa Bay at 36.1%. $179.2M has traded across 2 outcomes on Kalshi and Polymarket. The market is expected to resolve by Oct 31, 2028.

Kalshi event status: open

Questions

What does the consensus price mean?

It is the price of a Yes contract that pays $1 if the outcome happens. A 14¢ price means traders put the chance near 14%. Where two venues list the same outcome, we blend their last prices, weighting the venue with more trading volume more heavily (neither counts for less than a quarter). When only one outcome can win, each venue’s prices add up to a little over 100% (its margin); the fair chance removes that margin so the outcomes add up to exactly 100%.

How is the payout worked out?

A Yes contract pays $1 if it wins, so at the best ask a $100 stake buys 100 ÷ ask contracts. At 18¢ that is about 555 contracts, paying $556 (5.56x) if Yes happens. Venue fees and price slippage on larger orders are not included.

Why do the venues show different prices?

Each venue has its own traders, fees and order book. Contracts can also settle on slightly different terms, which is why each row lists how closely the rules match.

Is a price gap an arbitrage?

Only when you can buy Yes on one venue below what someone pays for Yes on the other, after fees, and both contracts settle the same way. We show the executable bid and ask so you can check.

How fresh are these prices?

Venue prices refresh every few minutes, and the order book and live quotes stream continuously. Each venue’s card shows when we last observed it.

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