The scarcity of magnitude 9.0+ events underpins the 93.2% market-implied probability of “No” before 2027. USGS historical catalogs document only five instrumentally recorded M9+ earthquakes since 1900, with recurrence intervals for megathrust ruptures typically spanning 25–50 years or longer based on paleoseismic records. The most recent was the 2011 Tōhoku event; recent 2026 activity monitored by the USGS has included several M7–7.7 quakes but no trend toward the multi-segment failure required for a full-margin 9.0 rupture. With only months remaining until December 31, 2026, the brief window reinforces trader consensus. An unforeseen event in a high-strain subduction zone such as Cascadia could still shift odds, though current geophysical data show no precursors indicating imminent escalation.