Houthi forces' rapid September 2026 advances along Yemen’s Red Sea coast, including seizure of Mokha port, Perim (Mayyun) Island, and nearby islands, have given the group direct oversight of the Bab el-Mandeb approaches and enabled targeted strikes on vessels, particularly those linked to Saudi Arabia. This has driven a sustained 26–60% reduction in daily ship transits from pre-crisis levels, with IMF PortWatch data showing roughly 9–30 vessels per day in early October amid higher insurance premiums and widespread rerouting around the Cape of Good Hope. No formal closure declaration has occurred, and traffic has not yet reached the low thresholds (such as a 7-day average of 10 or fewer arrivals) that define effective closure in related prediction markets. Saudi-backed counteroffensives and regional diplomatic statements continue, while escalation risks remain tied to broader Red Sea and Hormuz dynamics. Traders currently price a modest probability of full effective closure by year-end, reflecting the gap between territorial control and a complete halt in commercial movement.