Prediction market bettors give only a 27% chance that the Strait of Hormuz returns to normal shipping by the end of April, down 42 percentage points from earlier levels, suggesting traders increasingly expect the waterway's closure to drag well into the summer.
The narrow channel between Iran and Oman through which roughly 20% of the world's oil trade normally passes has been largely blocked since late February, when the United States and Israel launched military strikes against Iran.
Data from Polymarket, the prediction market platform where traders bet real money on real-world outcomes, shows the probability of normalisation rising only gradually across successive monthly contracts: 67% by end of May and 74% by end of June, implying markets assign a meaningful chance the disruption extends beyond the summer.
The May contract, which carries the heaviest trading volume at nearly $957,000, has surged 30 percentage points in recent sessions, suggesting money is only now beginning to price in a late spring resolution with any conviction.
A two-week ceasefire agreed on 8 April was supposed to reopen the waterway, but Iran continued to restrict and condition passage, demanding ships coordinate with its forces and, in some cases, pay a toll.
President Trump called the demands extortion and responded by imposing a naval blockade of Iranian ports, which entered its fourth day on Thursday, with the US Navy reporting it had turned back 14 vessels.
An estimated 230 loaded oil tankers remain stranded inside the Gulf, according to the Abu Dhabi National Oil Company chief, with tanker traffic through the strait reduced to near standstill.
Iran has threatened to extend disruption to the Gulf of Oman and the Red Sea in retaliation, while an initial round of US-Iran peace talks failed at the weekend.