The reopening contracts round-tripped a deal oil never priced

Brent moved +0.21% on the 5 August deal-imminent report — the 6th percentile of crisis days. Polymarket’s year-end leg moved 14 points, and printed an all-time low of 42.5% today.

Published 2026-08-17 · analysis

On 5 August the US, Iran and Oman were reported to be close to a deal to reopen the Strait of Hormuz, with the president saying an agreement could come within days. Brent closed at $86.65 against $86.47 the session before: +0.21%. Measured against 1,795 pre-crisis trading days back to 2019 that is the 8.5th percentile of daily moves; against the 113 crisis trading days since 28 February, the 6.2nd. It is also the only entry in the deal family with no other major event inside its ±7-day window — the cleanest read of a deal announcement the file contains. Oil declined to trade it.

The reopening contracts traded it. Polymarket’s reopen-by-31-December leg went from 47.5% on 1 August to 61.5% on 5 August, a 14-point move, 11 points of which came on 2 August alone — the day of the post saying Iran and other Middle Eastern countries had asked the US to hold off an attack, three days before the deal report. Kalshi’s reopen-before-January-2027 contract ran 37% to 53% by 6 August, 16 points.

Today both sit below where the rally started, and at the lowest prices either has ever printed. Polymarket closed at 42.5%: five points under 1 August, 19 under the 5 August high, and the weakest of the 99 days since the contract opened at 80.5% on 11 May. Kalshi closed at 33%: four points under 1 August, 20 under its high, and the lowest of 153 days since it opened at 96% on 18 March. Fourteen and sixteen points, put on and taken off inside twelve days, ending lower than they began.

This is the second round trip of the same shape. Into the Islamabad Memorandum signed on 17 June — the deal that formally ended the war and the blockades — Polymarket rose from 71.5% on 10 June to 90.5% on the 16th, 19 points. Brent’s move on the day of the signing was −0.21%: again the 8.5th percentile of pre-crisis days. That contract now trades 48 points below that peak. Attribution caveat: three other major events sit inside the June signing’s ±7-day window, so its reaction is not cleanly separable; the August one has none.

Only the first deal ever cleared the tape. The two-week ceasefire of 8 April, tied explicitly to reopening the strait, took Brent down 11.65% in a session — a larger one-day move than 99.1% of pre-crisis days. Nothing since has come close. What oil did do over the last twelve days was rise 7.9%, from $86.47 on 4 August to $93.26 on 11 August, the last official close in the file — and it did that across the weekend the UAE says an Iranian missile hit an ADNOC tanker in the strait, not across the diplomacy. The flat print on the 5th was not oil asleep. It was oil refusing the announcement, and it has had nothing to take back since.

One more reading on the year-end leg. At 42.5%, Polymarket has now fallen to roughly the price at which the average dated reopening market opened: 43.8% across the twelve that have resolved, every one of them NO. Four and a half months into a closed strait, with the near-dated 31 August contract down to 1.25% from a 41.5% open, the year-end market is only now as pessimistic as its dead predecessors were on day one.

Open this piece in the interactive site (charts, timeline, related events) →