TOTAL VOLUME:

$134b

24H VOL:

$87,176,691

24H TRANSACTIONS:

2,388,728,490

OPEN INTEREST:

$1,391,958,194

394,660

Markets across

30,119

events

MATCHED EVENTS:

2,626

PLATFORM COVERAGE:

5

Polymarket:

39%

VS.

Kalshi:

61%

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S&P 500 (SPX) Up or Down on March 18?
polymarket
kalshi

S&P 500 (SPX) Up or Down on March 18?

Volume:
$122,365

6,600 or above

 - Kalshi

6,600 or above - Kalshi

1W

News

Positive

Negative

Neutral

Hover marker for details

Vol.

·

Resolved Apr 18, 2026

Closed: Mar 18, 7:00 PM EST

kalshi

Kalshi

View
Join Kalshi and score $25 for your first trade.
Outcome
Trade
Chance %
Price
Spread
Liquidity
Volume
24h
7d
Open Interest
Ends in
Result
kalshi

6,600 or above

View
100%
Yes 100¢No 0¢
—
N/A
$18,208
N/A
N/A
$17,788
Settled
Yes
kalshi

6,550 or above

View
100%
Yes 100¢No 0¢
—
N/A
$238
N/A
N/A
$218
Settled
Yes
kalshi

6,525 or above

View
100%
Yes 100¢No 0¢
—
N/A
$164
N/A
N/A
$149
Settled
Yes
kalshi

6,200 or above

View
100%
Yes 100¢No 0¢
—
N/A
$100
N/A
N/A
$100
Settled
Yes
kalshi

6,575 or above

View
100%
Yes 100¢No 0¢
—
N/A
$93
N/A
N/A
$64
Settled
Yes
kalshi

6,050 or above

View
100%
Yes 100¢No 0¢
—
N/A
$69
N/A
N/A
$69
Settled
Yes
kalshi

6,475 or above

View
100%
Yes 100¢No 0¢
—
N/A
$36
N/A
N/A
$16
Settled
Yes
kalshi

6,500 or above

View
100%
Yes 100¢No 0¢
—
N/A
$35
N/A
N/A
$20
Settled
Yes
kalshi

6,375 or above

View
100%
Yes 100¢No 0¢
—
N/A
$25
N/A
N/A
$11
Settled
Yes
kalshi

6,300 or above

View
100%
Yes 100¢No 0¢
—
N/A
$21
N/A
N/A
$21
Settled
Yes
kalshi

6,350 or above

View
100%
Yes 100¢No 0¢
—
N/A
$21
N/A
N/A
$21
Settled
Yes
kalshi

6,325 or above

View
100%
Yes 100¢No 0¢
—
N/A
$21
N/A
N/A
$21
Settled
Yes
kalshi

6,425 or above

View
100%
Yes 100¢No 0¢
—
N/A
$16
N/A
N/A
$5
Settled
Yes
kalshi

6,400 or above

View
100%
Yes 100¢No 0¢
—
N/A
$16
N/A
N/A
$5
Settled
Yes
kalshi

6,450 or above

View
100%
Yes 100¢No 0¢
—
N/A
$15
N/A
N/A
$5
Settled
Yes
kalshi

6,625 or above

View
0%
Yes 0¢No 100¢
—
N/A
$46,569
N/A
N/A
$32,335
Settled
No
kalshi

6,650 or above

View
0%
Yes 0¢No 100¢
—
N/A
$23,409
N/A
N/A
$8,282
Settled
No
kalshi

6,675 or above

View
0%
Yes 0¢No 100¢
—
N/A
$17,198
N/A
N/A
$8,490
Settled
No
kalshi

6,700 or above

View
0%
Yes 0¢No 100¢
—
N/A
$8,288
N/A
N/A
$4,053
Settled
No
kalshi

6,725 or above

View
0%
Yes 0¢No 100¢
—
N/A
$3,679
N/A
N/A
$1,786
Settled
No
kalshi

6,750 or above

View
0%
Yes 0¢No 100¢
—
N/A
$2,433
N/A
N/A
$1,416
Settled
No
kalshi

6,775 or above

View
0%
Yes 0¢No 100¢
—
N/A
$971
N/A
N/A
$629
Settled
No
kalshi

7,000 or above

View
0%
Yes 0¢No 100¢
—
N/A
$425
N/A
N/A
$425
Settled
No
kalshi

6,800 or above

View
0%
Yes 0¢No 100¢
—
N/A
$198
N/A
N/A
$177
Settled
No
kalshi

6,825 or above

View
0%
Yes 0¢No 100¢
—
N/A
$58
N/A
N/A
$43
Settled
No
Total markets: 25 of 61

Description

This event group tracks whether the S&P 500 Index closes higher or lower on March 18, 2026 compared to the prior trading day (Polymarket) versus absolute price thresholds (Kalshi). The two platforms use fundamentally different resolution mechanics: Polymarket measures directional movement relative to the previous close, while Kalshi resolves based on fixed price levels.

PredictionHero - Resolution Divergence Alerts (RDA)

Divergence Detected

Issue: Polymarket uses relative directional resolution (vs prior close), while Kalshi uses absolute price level thresholds. These represent two distinct event definitions that may produce conflicting outcomes depending on the March 18 closing price and prior trading day close.Hero tip: Do not assume these markets are fungible. Polymarket Up/Down is a directional bet; Kalshi thresholds are absolute level bets. A market that moves up in absolute terms but down relative to the prior close will resolve differently on each platform. Cross-platform arbitrage is possible but requires careful threshold mapping.

Critical divergence points:

  • Polymarket: Resolves based on directional comparison: Up if March 18 close > prior trading day close; Down if < prior close; 50-50 if equal or no trade. Uses WSJ Historical Prices as official source. Handles shortened sessions and trading halts by using last valid on-exchange trade price.
  • Kalshi: Resolves based on 60 absolute price thresholds, each independently resolving Yes if end-of-day SPX > threshold value (e.g., above 6999.9999, above 7024.9999, etc.). No relative comparison; no directional logic. All thresholds use identical resolution criteria.
Our PredictionHero Resolution Divergence Alerts (RDA) are there to help users identify potential differences across platforms. They do not replace or supersede the official rules and description of any prediction market. Users are solely responsible for reviewing and understanding the applicable rules and resolution criteria before placing any trade or bet. If you notice a potential inconsistency, discrepancy, or error in an alert, please report it to our team so we can review and improve the accuracy of our data.