Will __ ships transit the Strait of Hormuz on any day by May 31?

The core uncertainty centers on what IMF Portwatch counts as "Arrivals of Ships" for the Strait of Hormuz and how comprehensive that coverage is; if the dataset records only port calls at a small set of monitored locations rather than every vessel transiting the waterway, typical daily counts are likely to be well below 20, which pushes the baseline probability of a >=20 day low. The market price (Yes 8.5%) and the very large event volume indicate market participants overwhelmingly expect No, which is consistent with a belief that the Portwatch series rarely or never reaches 20 on any single day; I start from that market-informed baseline but adjust slightly upward to reflect possible reporting quirks and exceptional real-world traffic surges.

External factors can create occasional spikes: concentrated tanker movements, repositioning of merchant fleets, or a one-off surge in arrivals tied to port scheduling or disruptions elsewhere could produce a day with an unusually high number of arrivals, and IMF Portwatch’s allowance for revisions made during the market timeframe means a later correction could retroactively produce a qualifying data point. Conversely, geopolitical disruptions, sanctions, or temporary rerouting of traffic away from the Strait of Hormuz would suppress arrivals, making a >=20 day less likely; overall, these drivers are asymmetric because spikes are rarer but possible while suppression is more continuous and probable.

Data-quality and publication-timing risks matter materially: if IMF Portwatch has gaps, different update cadences, or conservative inclusion rules, the probability of observing a published >=20 day falls further; additionally, the market closes today (May 31, 2026), so whether Portwatch has already published data for recent dates and whether any in-window revisions are still allowed affects resolution chances in the short run. Given these considerations, a modest uplift above the market-implied 8.5% to 12% captures the non-negligible chance of a reporting anomaly or rare traffic surge while still reflecting the strong evidence, market sizing, and conceptual reasons to expect counts below 20 on most days.