Rocket Lab’s repeated emphasis on Q4 2026 pad delivery rather than liftoff, combined with ongoing first-stage qualification testing for its reusable Neutron vehicle and Archimedes engines, underpins the 93.5% market-implied probability against a launch by year-end. A January tank rupture already shifted prior mid-year targets, and recent SEC filings plus earnings commentary explicitly note the narrowing end-of-2026 window while prioritizing a production-ready system capable of rapid cadence. Remaining hydrostatic and hot-fire milestones later this year introduce schedule risk typical of new medium-lift rockets. A successful late-year test sequence could still enable a December flight, though historical slips and the company’s focus on post-debut reliability make that outcome unlikely.