Probable forecastOpen
The US-Iran Ceasefire Deal
The deal is real and signed, but Trump's own public caveat that he could resume attacks keeps the probability of full durability well below certain.
Probable’s read
Low confidence. Synthesized from prediction markets, professional analysts, public opinion, and official data.
Market cross-check: 49% — Probable's read differs by 13 points, for the reasons below.
Ceasefire agreements involving the US and a regional adversary hold through a six-month window more often than not historically, but Trump said explicitly he could still resume attacks, per Reuters, and Axios characterized the deal as one that 'falls short of his promises' — both factors elevate resumption risk. The Manifold market on the deal text being released by June 19 is at 99%, confirming the agreement is genuine, but no market prices the durability question directly. Probable sets 62% with a wide range of 45 to 76 percent.
What’s likely. AP News and Reuters both report that US and Iranian presidents signed an initial ceasefire agreement covering the Strait of Hormuz, sanctions relief, and Lebanon, with nuclear talks continuing separately. CNN published an annotated version of the 14-point plan. However, Reuters also reported that Trump said he 'could still resume attacks,' and Axios noted the deal 'falls short of his promises,' including on Iran's ballistic missile program. BBC reported UK Prime Minister Starmer pledged to help reopen the Strait of Hormuz, suggesting allied buy-in. The New York Times framed the outcome as Iran having defied Trump's demand for unconditional surrender, and multiple outlets including Foreign Policy and Bloomberg described it as a diplomatic setback for the US.
What the markets say
A Manifold market on whether the US-Iran deal text would be released by June 19 was priced at 99% as of today, confirming traders viewed the agreement as effectively done.
Source: ManifoldPolymarket traders put the probability of the Iranian regime falling by June 30 at essentially 0%, suggesting the deal stabilizes rather than topples the Tehran government.
Source: Polymarket
How Probable got to 62 percent
The Manifold market at 99% on deal-text release confirms the ceasefire is real, and the Polymarket regime-collapse market at 0% confirms traders do not expect imminent Iranian government collapse. Those two signals together suggest the deal is genuine and the Iranian government has reason to hold it. Against that, Trump's own public statement — reported by Reuters — that he could still resume attacks is an unusually direct threat to durability from the signatory himself. Probable weights the 62% estimate toward the middle of the realistic range precisely because the political will on the US side is openly conditional.
Why it matters to you
NPR reported that the Iran war has already wiped out 1.5 years of wage growth and rewired global energy markets, according to the Economic Policy Institute — so the durability of this ceasefire has direct consequences for inflation and global supply chains.
What to watch
Watch whether the Strait of Hormuz reopens on schedule: BBC reports the UK is committed to that process, and any delay or incident in the strait would be the clearest early signal that the deal is fraying.
Further reading
The question we’re forecasting
Will the US-Iran ceasefire agreement signed on June 18, 2026 remain in effect — with no resumption of US military strikes against Iran — through December 31, 2026?
Resolves by June 19, 2026 — then we grade it yes/no on the scoreboard.
From the briefing
This forecast was published in Probable’s briefing on Thursday, June 18, 2026: Thursday on Probable — The US-Iran ceasefire is signed, the Fed signals rate hikes, and Bernie Sanders wants the public to own AI.
Probable’s forecasts synthesize prediction markets, professional analysts, public opinion, and official data. Drafted with AI from cited sources. Reviewed before publishing. Not financial advice. Methodology · Spot an error?