Avengers: Doomsday’s record-shattering presales—already exceeding $70 million domestically with weeks to go—drive its 74.5% implied probability for the biggest 2026 domestic opening weekend. Early tracking from Box Office Theory points to a $340–410 million debut that could surpass Spider-Man: Brand New Day’s July record of $360.1 million, fueled by Russo brothers direction, Robert Downey Jr. as Doctor Doom, and broad MCU fan momentum ahead of the December 18 release. Spider-Man: Brand New Day’s prior achievement accounts for its 25.5% share but sits in the rearview. The Hunger Games: Sunrise on the Reaping and Dune: Messiah trail at 0.1% each, with Thanksgiving tracking around $60–80 million and a competing $90–100 million IMAX-focused debut, respectively, leaving little room for an upset.