Dark Knight holds off Mummy at the top of the box office for third weekend

"The Dark Knight" fended off a strong challenge from the new "Mummy" sequel to lead the North American box office for a third weekend, and is on track to become the second-biggest movie of all time.

The Batman blockbuster earned $43.8 million for the three days beginning Friday, distributor Warner Bros. Pictures said on Sunday. Universal's "The Mummy: Tomb of the Dragon Emperor" followed with $42.5 million.

The Walt Disney Co. political comedy "Swing Vote" came in at No. 6 with just $6.3 million, the latest disappointment for its star, Kevin Costner, who has not had a $100 million movie since 1992's "The Bodyguard."

The total for "The Dark Knight" rose to $394.9 million. Warner Bros., a unit of Time Warner Inc, said it expects the film to add at least $100 million, surpassing the $461 million haul of 1977's "Star Wars" and its two reissues, the current No. 2 movie of all time in the United States and Canada.

The $601 million record, held by 1997's "Titanic," seems watertight. Adjusted for inflation, though, "Titanic" ranks at No. 6, far behind "Gone with the Wind" at $1.4 billion, according to tracking firm Box Office Mojo.

"The Dark Knight" will add yet another record to its impressive tally on Monday or Tuesday, when it breaks $400 million, which would be its 18th or 19th day of release. The old record of 43 days is held by 2004's "Shrek 2."