The S&P 500 and Nasdaq closed at all-time highs while the US-Iran conflict continues. The Polymarket contract for the S&P 500’s April 15 open is at 99.9% YES, up from 57% yesterday.
Market reaction
The jump from 57% to near-certainty reflects traders betting on a US-Iran ceasefire, even with the Strait of Hormuz closed and inflation rising. The April 15 contract saw $142,292 in face value and $114,324 in actual USDC traded. The largest price move was a 22-point drop at 12:02 PM, consistent with volatility around geopolitical developments.
Why it matters
Odds at 99.9% mean the market has almost fully priced in the S&P 500 opening higher on April 15. A YES share at 99¢ pays $1 if correct, leaving almost no upside at current levels. The 42-point swing from yesterday’s 57% signals that traders moved rapidly toward expecting diplomatic resolution rather than escalation.
What to watch
Official statements on the Strait of Hormuz or new diplomatic initiatives between the US and Iran could shift sentiment. At 99.9%, the contract has almost no room to move higher, so the asymmetric risk is to the downside if negotiations stall or hostilities resume.
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Spx Opens Up Or Down On April 15 2026| Contract | Odds | Δ since publish | Volume 24h | |
|---|---|---|---|---|
| April 15 | 99.9% | — | — | Trade → |
| Contract | Odds | Δ since publish | Volume 24h | |
|---|---|---|---|---|
| April 14 | 100% | — | — | Trade → |
