US-Iran nuclear deal by May 31?

Platform comparison

Market context

Negotiations between the United States and Iran over nuclear programme restrictions have stalled since the Trump administration withdrew from the Joint Comprehensive Plan of Action (JCPOA) in 2018. A fresh bilateral or multilateral agreement by May 2026 would require a significant diplomatic reversal, particularly given Iran's continued uranium enrichment and the current US administration's hardline posture. The 19% implied probability reflects the low baseline likelihood of such a breakthrough within the settlement window, though the market does price in a non-negligible tail risk of unexpected diplomatic movement.

Historical precedent offers limited optimism. The original JCPOA took roughly two years of intensive negotiations (2013–2015) to conclude, and its collapse demonstrates how fragile such agreements can be. However, the 2015 deal itself emerged from a period of apparent stalemate, suggesting that rapid shifts in negotiating positions are possible. Comparable markets on Kalshi and Smarkets show similar probability ranges (18–21% implied), whilst Betfair's decimal odds (around 5.5–6.0) align with the same consensus. Polymarket's fee structure (2% maker, 2% taker) and KYC requirements remain less restrictive than Kalshi's US-only access, making it the preferred venue for international traders tracking this outcome.

Key catalysts include any formal announcement of resumed talks, changes in US or Iranian leadership priorities, and developments in UN Security Council resolutions or sanctions regimes. Reuters and Bloomberg regularly cover diplomatic signals; traders should monitor statements from the US State Department and Iranian foreign ministry closely. The resolution criterion requires only a publicly announced mutual agreement, not ratification or implementation, lowering the bar slightly compared to markets demanding full treaty entry into force.

Methodology

This page compares US-Iran nuclear deal by May 31? specifically across Polymarket, Kalshi, Betfair Exchange and Smarkets. Live odds come from the Polymarket order book; the other venues' contract details are maintained manually because their APIs aren't directly comparable. Every CTA routes to PolyGram, which mirrors the Polymarket order book at 0% fees.

Resolution & payout

Settlement is the biggest difference between the four platforms: Polymarket on-chain in USDC (instant), Kalshi USD via CFTC (T+1), Betfair and Smarkets in local currency via bank withdrawal (T+1 to T+3). PolyGram routes every trade directly into Polymarket's on-chain settlement, which is why payouts land fastest.

FAQ

Is this market available outside the US?

PolyGram is available in most jurisdictions where Polymarket isn't directly accessible. Polymarket itself is geo-blocked in the US/UK/EU. Always check local regulations.

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.

How fast are USDC deposits?

Polygon credits deposits after 12 confirmations — usually under 30 seconds. Withdrawals follow the same path and land back in your wallet within minutes.

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.