December 18 Puts "Avengers: Doomsday" and "Dune: Part Three" on the Same Day. Only One Gets IMAX.

Avengers: Doomsday and Dune: Part Three open on the same day — Friday, December 18, 2026 — and only one of them gets IMAX. The collision has had a name since the trailer dropped: Dunesday.

What Marvel is betting

Doomsday is the fifth Avengers film, directed by Anthony and Joe Russo — the pair behind Infinity War and Endgame — and built around the most discussed casting decision in modern franchise film: Robert Downey Jr. returns to the Marvel Cinematic Universe not as Iron Man but as Victor von Doom. The cast pulls together the Avengers, the Fantastic Four and the Fox-era X-Men in one film for the first time. It is the first half of a two-part finale; Avengers: Secret Wars follows on December 17, 2027.

The date was not an accident, and neither was holding it. The film moved from an original May 1, 2026 slot to December 18 and has not moved since. Marvel is treating the holiday corridor — the strongest sustained moviegoing stretch of the year — as home turf, and pre-sales have been open for months. Tracker figures reported by Forbes put worldwide pre-sales past $125 million by the end of October; treat that as a tracker estimate rather than a Disney number, but the direction is not in doubt.

The screen problem

Here is the part the marketing doesn't say out loud. Reporting on the release has Dune: Part Three holding a three-week exclusive on IMAX screens — the premium format where event films make their most profitable money. If that holds, the biggest Marvel film in years opens without the biggest screens in the market, in the same weeks when its audience most expects them. One of these studios will have the format that sells out; the other will have the conversation. December 18 grades both strategies at once.

Studios have run this experiment before, usually by blinking: one title moves. Neither has. Warner Bros. is backing the Dune franchise's premium-format identity; Disney is backing the proposition that an Avengers event is format-proof.

What to watch

Three things, in order: which film takes the opening weekend (the other's studio will call it a marathon by Monday); the second-weekend drop, which is where the holiday corridor either multiplies a hit or exposes a front-loaded one; and the IMAX split in week two, when theatre chains can start re-allocating screens to whichever film is filling them. Our explainer on what an opening-weekend gross actually means — linked below — covers how to read all three without the spin.