‘Dark Knight’ may be summer’s highest-grossing film

It smashed the weekend box-office records. But a closer look at “The Dark Knight’s” performance suggests that the Batman sequel is poised to be the summer’s -- if not the year’s -- highest-grossing release.

While the final theatrical take for “The Dark Knight” won’t be known for many weeks, insight into the sequel’s ultimate appeal emerged early Sunday, when rival studios were arguing over how much weekend business the film was doing.

Attendance at almost all movies drops sharply from Saturday to Sunday, and studios typically predict a movie’s Sunday -- and thus total weekend -- gross by assuming the film will generate between 75% and 85% of its Saturday sales on Sunday (because weekend box-office estimates are issued on Sunday morning, they necessarily are based on such projections).

“The Dark Knight” had grossed about $48 million on Saturday, and distributor Warner Bros. was estimating it would fall about 18% on Sunday, giving it a total weekend haul of $155.3 million. Other studios on Sunday morning, however, reckoned “The Dark Knight” would sink more than 20% from Saturday to Sunday, meaning that the Batman sequel would narrowly -- if at all -- break the all-time weekend record of $151.1 million held by 2007’s “Spider-Man 3.”

By Monday morning, though, moviegoers proved everybody wrong: “The Dark Knight” didn’t fall 20%. It didn’t fall 15%. It didn’t even fall 10%. It slipped around 9%, a figure rival distributors said Monday was unheard-of.

Such steadfast audience interest not only gave “The Dark Knight” an even greater opening weekend record -- $158.3 million -- but also proved the movie has enough positive word of mouth to become the summer’s highest-grossing film.

“I think that’s not going to be a difficult task,” Warner Bros. domestic distribution chief Dan Fellman said of “The Dark Knight’s” prospects to eclipse both “Iron Man” ($314.4 million to date) and “Indiana Jones and the Kingdom of the Crystal Skull” ($312.6 million to date). “I think we’re going to be way up there.”

But how high? Some rival studios said Monday that they are confident “The Dark Knight” could gross more than $400 million by the time all tickets are counted. The highest-grossing film of all time is 1997’s “Titanic,” with ticket sales of $600.8 million. But only six other films ever have grossed more than $400 million in domestically, a list that includes the original “Spider-Man” and “E.T. the Extra-Terrestrial.”

“The Dark Knight’s” Sunday sales -- a record of $43.6 million for the day -- suggests that family, adult and ethnic interest in the film is unusually high, as the end of the weekend tends to be an especially good moviegoing day for those demographics. Warner Bros. said some teenage moviegoers already have seen the movie multiple times.

Yet what’s really going to work in Warner Bros.’ favor is the competitive landscape, which should allow “Knight” to win at least one more weekend and rack up many more millions during the week.

On Friday, 20th Century Fox releases “The X-Files: I Want to Believe” while Sony has Will Ferrell and John C. Reilly’s R-rated comedy “Step Brothers.” The former film may not gross $20 million in its debut, while the latter may get to $30 million, according to data from audience tracking surveys. So even if “The Dark Knight” drops 50% from its opening weekend next week, it would easily finish first.

Lost in all the “Dark Knight” headlines was the performance of “Mamma Mia!” While the film grossed $27.8 million in its debut weekend in domestic theaters, the ABBA musical is selling a flood of tickets overseas. On its current pace, “Mamma Mia!” may gross as much as $100 million domestically but could sell nearly $300 million in tickets abroad.

john.horn@latimes.com