War-risk insurance is the specialist cover a ship needs to sail through a conflict zone, priced as a percentage of the vessel’s hull value per voyage. In peacetime it is a rounding error, roughly 0.25 per cent of hull value or less. In a live conflict it can reach several per cent per transit, and because no charterer will sail uninsured, the quote effectively decides whether trade moves at all. That makes a small market of Lloyd’s and specialty underwriters one of the most powerful, least watched forces in commodity pricing.
How the pricing works
Standard hull and cargo policies exclude acts of war, so vessels entering designated “listed areas” buy separate war-risk cover, quoted per voyage and repriced as often as weekly. The premium responds to demonstrated threat rather than headlines: an actual strike on a commercial vessel moves quotes by multiples, while diplomatic noise barely registers. Underwriters pay real claims on real hulls, which is why their pricing is often earlier and blunter than the futures market’s. In July 2026, cover for a Strait of Hormuz transit repriced from about 0.25 per cent to as much as 5 per cent of hull value after missile strikes on two tankers: on a $100 million vessel, from roughly $250,000 to $10 million for a single passage.
Why it can close a waterway that stays open
A strait can be closed economically long before it is closed militarily. When the premium consumes the margin on a cargo, marginal sailings stop; when underwriters withdraw cover entirely, sailings stop regardless of price. The result is an invisible blockade: no fleet, no mines, just actuarial arithmetic throttling flow. History runs from the 1980s tanker wars through the 2024 Red Sea diversions to the 2026 Hormuz contraction, and in each case insurance was the mechanism through which risk became reduced volume. For markets, the practical lesson is that war-risk quotes and weekly transit counts lead the oil price, in both directions: premium decay is usually the first hard evidence of de-escalation, ahead of any communiqué.
What to watch
The quoted premium as a share of hull value for the affected area (and whether cover is available at all), weekly transit counts from tanker trackers, freight rates for vessels still willing to sail, and the gap between the insurance move and the crude move. When insurance reprices by multiples while the futures curve barely shifts, one of the two markets is wrong, and the claims-paying one has the better record.