Polymarket shows 22% chance of Bab el-Mandeb Strait closure by December 31

One of the most important waterways on Earth now has a one-in-five chance of being effectively closed before year’s end, according to traders on Polymarket. The decentralized prediction market currently assigns a 22% probability that the Bab el-Mandeb Strait, the narrow passage connecting the Red Sea to the Gulf of Aden, will grind to a functional halt by December 31, 2026. For anyone who doesn’t have a shipping map memorized: roughly 12% of global trade normally passes through this strait. When it slows down, everything from oil tankers to container ships has to take the long way around Africa, adding weeks and billions in costs. What counts as “closed” Polymarket’s contract uses a specific, measurable definition. The strait resolves as “effectively closed” if the International Monetary Fund’s PortWatch tool shows a 7-day moving average of ship arrivals falling to 10 or fewer. That’s a high bar, and it hasn’t been hit yet. Current ship transits have already dropped dramatically from pre-crisis levels, with daily crossings halved on some days to roughly 15 vessels. That’s 40-60% below where traffic sat before Houthi forces began targeting commercial shipping. But 15 is still above ...