Strait of Hormuz on Polymarket and Kalshi: how the markets settle

What every Hormuz market settles on

Polymarket and Kalshi both settle their Hormuz traffic markets on IMF PortWatch's daily count of transit calls through the strait. PortWatch builds that count from AIS, the radio transponders ships carry, and adds up five types of ship: container, dry bulk, general cargo, roll-on/roll-off and tanker. Polymarket's rules name the series as transit calls ('Arrivals of Ships'); Kalshi's call it transit calls. It is the same number.

That matters because the strait is in a war zone. PortWatch's own Hormuz page warns of GPS jamming, AIS spoofing and vessels going dark, and asks users to treat the data with care. A ship that crosses with its transponder off, and that PortWatch does not report, does not count towards any of these markets.

The rules side by side

As read from each venue on 9 November 2026, for the markets listed that day. Rules change, so check the market before you trade.

Note the gap at 60: Kalshi pays above 60, Polymarket at 60 or more, so a published 60.0 pays on one and not the other. Note the windows too. PortWatch's 7-day average reached 31.9 on 29 June 2026, above the lowest line in Kalshi's 2026-average market, but that market counts only from 6 July. And note what is not here: barrels, cargo value, or any count but PortWatch's.

The Tuesday clock

PortWatch updates its daily chokepoint data once a week, on Tuesdays at 9 AM Eastern, according to its data page. Each release adds the days since the last one, so a ship that crosses early in a week can take more than a week to appear in the data.

Kalshi's weekly markets say they will settle "no earlier than Tuesday at 9 AM following the end of the period, once complete data is available". Polymarket's resolve as soon as PortWatch publishes the dates they need; if those dates have not appeared within 14 calendar days, they resolve on whatever has been published.

In between, the markets trade on everything except the settling number: AIS trackers, official claims, satellite pictures and rumour. That gap is where most of the argument happens.

Revisions: when a published day changes

PortWatch figures can change after they are published, and the venues treat later changes differently.

• Polymarket. The return-to-normal markets consider revisions published within the market's timeframe, but a revision never disqualifies a value that has already qualified. Revisions made after the final date's data is published are ignored.
• Kalshi. The value is fixed when the market settles. The contract terms linked from each market set out how revisions are handled.

Aureum reads the PortWatch feed for the strait every morning and records every change to a day already published, so a restatement shows up as a restatement rather than a silent edit.

What normal was

Both venues use 60 transit calls a day, as a 7-day average, as their bar for normal. PortWatch's own series shows how traffic ran in the years before the war, and how often it cleared that bar.

So 60 was a bar that peacetime traffic sometimes missed. From 2019 to 2025, every day the 7-day average sat below 60 fell between November and April, and 36 of the 372 full weeks from January 2019 to February 2026 totalled fewer than 420 transit calls, the weekly equivalent of 60 a day. Winter is the quiet season: a recovery that arrives in December could still leave a 'normal by 31 December' market short.

Reopening headlines against the PortWatch count

Iran has declared the strait open more than once since the war began. The markets pay on what PortWatch prints afterwards, and so far those prints have never come close to 60.

Why the counts disagree

On any given day you can find several Hormuz numbers, and they rarely agree. Only one settles these markets. The examples below are dated, because each of these sources moves on its own clock.

EIA warns that AIS data for the strait have been "especially unreliable" since the end of February 2026. That cuts both ways: PortWatch can undercount ships that go dark, and the markets pay on the undercount. More on how each count is built is in the Strait of Hormuz guide.

Reading the number before Tuesday

PortWatch counts AIS transit calls. Counting the same kind of signal at the strait every day gives an early read on what PortWatch will publish. How close that read gets depends on where the counting line sits, which ships are counted, and PortWatch's own restatements.

• Free AIS trackers publish daily crossing counts for the strait, often with PortWatch's figures beside them once they land.
• Aureum's Hormuz board counts the large commercial ships that cross a fixed gate line each day, from their transponders. Yesterday's total is confirmed once the whole day is in, a provisional count runs through the day, and PortWatch's figures sit alongside as they land.
• None of these is the settling number. They all read transponders, so they miss the same dark ships PortWatch misses. Treat them as a forecast of PortWatch, and check how far each has run from PortWatch in past weeks before you lean on it.