The Prediction Markets

Measles cases in U.S. by October 31?

Closes
Nov 1, 2026, in 9 days
Traded
$1.2M
Venues
Polymarket, Kalshi
Prices updated
just now
Share

What the markets expect

4500+ 99.8%

Next is Above 5000 at 97%. The venues list this event, but none of their outcomes are matched yet, so prices are shown separately.

Odds by venue

Consensus blends each venue’s last price, weighted by how much has traded there. 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.

Prices come from our regular polls of each venue, the oldest 1 min ago. Ages are as of when this page was built.

  • Polymarket
  • Kalshi
4500+
99.8%
Polymarket 99.8%polled, 59s ago
Polymarket
Contract
4500+
Last price
99.8%
As of
Polled just now
Buy Yes
—
Sell Yes
99.6¢
Volume
$6K
Trade this on Polymarket
Above 5000
97%
Kalshi 97%polled, 1 min agoBest Yes 99¢ on Kalshi, $100 pays $101 (1.01x)
Kalshi
Contract
Above 5000
Last price
97%
As of
Polled 1 min ago
Buy Yes
99¢
Sell Yes
95¢
$100 on Yes pays
$101 (1.01x)
Trade this on Kalshi
4700+
96.4%
Polymarket 96.4%polled, 59s agoBest Yes 99.5¢ on Polymarket, $100 pays $101 (1.01x)
Polymarket
Contract
4700+
Last price
96.4%
As of
Polled just now
Buy Yes
99.5¢
Sell Yes
93.3¢
$100 on Yes pays
$101 (1.01x)
Volume
$4K
Trade this on Polymarket
4800+
95.8%
Polymarket 95.8%polled, 59s agoBest Yes 99.3¢ on Polymarket, $100 pays $101 (1.01x)
Polymarket
Contract
4800+
Last price
95.8%
As of
Polled just now
Buy Yes
99.3¢
Sell Yes
92.2¢
$100 on Yes pays
$101 (1.01x)
Volume
$5K
Trade this on Polymarket
Above 6000
84%
Kalshi 84%polled, 1 min agoBest Yes 86¢ on Kalshi, $100 pays $116 (1.16x)
Kalshi
Contract
Above 6000
Last price
84%
As of
Polled 1 min ago
Buy Yes
86¢
Sell Yes
84¢
$100 on Yes pays
$116 (1.16x)
Volume
$292K
Trade this on Kalshi
Above 7000
75%
Kalshi 75%polled, 1 min agoBest Yes 75¢ on Kalshi, $100 pays $133 (1.33x)
Kalshi
Contract
Above 7000
Last price
75%
As of
Polled 1 min ago
Buy Yes
75¢
Sell Yes
66¢
$100 on Yes pays
$133 (1.33x)
Volume
$2K
Trade this on Kalshi
4900+
64%
Polymarket 64%polled, 59s agoBest Yes 73¢ on Polymarket, $100 pays $137 (1.37x)
Polymarket
Contract
4900+
Last price
64%
As of
Polled just now
Buy Yes
73¢
Sell Yes
55¢
$100 on Yes pays
$137 (1.37x)
Volume
$6K
Trade this on Polymarket
Above 8000
34%
Kalshi 34%polled, 1 min agoBest Yes 34¢ on Kalshi, $100 pays $294 (2.94x)
Kalshi
Contract
Above 8000
Last price
34%
As of
Polled 1 min ago
Buy Yes
34¢
Sell Yes
33¢
$100 on Yes pays
$294 (2.94x)
Volume
$176K
Trade this on Kalshi
Above 9000
28%
Kalshi 28%polled, 1 min agoBest Yes 34¢ on Kalshi, $100 pays $294 (2.94x)
Kalshi
Contract
Above 9000
Last price
28%
As of
Polled 1 min ago
Buy Yes
34¢
Sell Yes
12¢
$100 on Yes pays
$294 (2.94x)
Volume
$360
Trade this on Kalshi
Above 10000
10%
Kalshi 10%polled, 1 min agoBest Yes 10¢ on Kalshi, $100 pays $1,000 (10.0x)
Kalshi
Contract
Above 10000
Last price
10%
As of
Polled 1 min ago
Buy Yes
10¢
Sell Yes
9¢
$100 on Yes pays
$1,000 (10.0x)
Volume
$169K
Trade this on Kalshi

Who resolves this market

Polymarket
Polymarket resolves via:
UMA optimistic oracle, source: cdc.gov
Kalshi
Kalshi resolves via:
Kalshi (CFTC-regulated exchange), source: CDC

How the odds have moved

The top 3 outcomes on both venues, with the consensus between them. Hover for exact values.

  • 4500+
  • Above 5000
  • 4700+

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.

Polymarket

Open on Polymarket ↗

Top of book

Connecting
Best bid
—
Spread
—
Best ask
—

Waiting for the first live quote…

Depth · top 8 levels

Loading snapshot…

Recent trades

Loading…

Kalshi

Kalshi doesn’t list 4500+ for this event.

What your stake buys

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

$
Buy

Loading both order books…

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 (other / general rate). Fee calculator. Estimates only, not advice.

About this market

Live prediction market odds for "Measles cases in U.S. by October 31?". 4500+ leads at 99.8%. Next is Above 5000 at 97%. $1.2M has traded across 10 outcomes on Kalshi and Polymarket. The market is expected to resolve by Nov 1, 2026.

This market will resolve to "Yes" if there have been the specified amount or more confirmed cases of Measles (Rubeola) in humans in the territory of the United States of America in 2026, according to the CDC case counter by October 31, 2026, 11:59 PM ET. Otherwise, this market will resolve to "No". The resolution source for this market will be the CDC Measles (Rubeola) counter 'Total Cases' in 2026 (see: https://www.cdc.gov/measles/data-research/index.html) at the resolution time. If the counter becomes unavailable, another credible source will be used. Note: Only cases reported by the CDC Measles (Rubeola) counter will qualify, regardless of reports from U.S. State agencies or other sources.

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.

More other markets

See all other markets