US-Iran nuclear deal by May 31?

Platform comparison

Market context

The United States and Iran would need to reach a publicly announced nuclear agreement by 31 May for this market to resolve Yes. The latest negotiating round has produced no visible breakthrough, and the baseline remains a very low-probability outcome: Iran is still seeking sanctions relief and recognition of some enrichment capacity, while Washington has repeatedly pushed for tighter limits and more intrusive verification. That gap matters because the market only counts an actual mutual agreement, not vague signals, intermediaries’ optimism, or an interim understanding.

The closest historical reference point is the 2015 JCPOA, which took years of talks, multilateral involvement and eventual high-level political cover before it was signed; even then, it required a clear convergence on enrichment limits, inspections and sanctions relief. The Trump administration’s 2018 withdrawal, and the later collapse of the deal’s remaining constraints as provisions expired in 2025, left little shared framework to revive. Recent reporting from the Arms Control Association noted that the February 2026 Iranian proposal did not satisfy Washington’s maximal demands, including no enrichment and dismantlement, which suggests the sides remain far apart. Since snapback leverage also expired in October 2025, the diplomacy is now working under weaker formal constraints than in past rounds.

Traders should watch for any announced meeting between senior U.S. and Iranian officials, a written proposal circulating through Oman or other intermediaries, and signs that either side has softened on enrichment or verification. A credible deal would likely need to address Iran’s stockpile of higher-enriched uranium, IAEA access, and sanctions sequencing, all of which are politically sensitive and time-consuming. With the deadline less than two weeks away, any movement would need to come quickly and be explicit; otherwise, the default remains no agreement by month-end.

Sources: 1 · 2 · 3 · 4

Methodology

This page reviews US-Iran nuclear deal by May 31? across five venues. We show live odds for Polymarket-based markets (sourced from the Polygon order book); for other venues we list platform attributes, since the comparable contracts are not exposed via a public API on every venue. Every CTA points at PolyGram — the application we operate, where you trade directly against the Polymarket order book at 0% fees.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

FAQ

Where can I trade this market with the lowest fees?

On PolyGram, which mirrors the Polymarket order book at 0% fees. Kalshi charges up to 7% per trade; Betfair Exchange takes 2-5% commission on net winnings.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

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.

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.