Spider-Man: Brand New Day commands 93.5% implied probability because the franchise's proven global draw, Tom Holland's star power, and established MCU audience loyalty position it as the clearest 2026 box office leader. Traders cite its summer release window, strong presale indicators, and historical Spider-Man performance as key supports, while Avengers: Doomsday at 5.5% reflects solid but secondary MCU momentum amid heavier competition and earlier scheduling. An upset would require Spider-Man to underperform due to mixed reviews, marketing missteps, or unexpected audience fatigue, allowing Doomsday or another title to exceed $1.5 billion through exceptional critical reception and word-of-mouth.