Harry Potter and the Half-Blood Prince raked in $79.5 million this weekend, according to studio estimates from Nielsen EDI. Released on Wednesday, Half-Blood Prince has earned $159.7 million in just five days.

Like the book series, the Potter films show little sign of wear or fan fatigue. Half-Blood Prince marks the sixth installment of the J.K. Rowling saga, yet it managed to score the biggest opening day of the franchise yet; it earned $58.2 million on Wednesday.

Of course, the not-so-boyish wizard has a lot to live up to: No picture in the franchise has earned less than $250 million.

One reason the series hasn't slowed: Its fan base is waving its financial wand. When the first film hit screens in 2001, preteens were Potter's core audience. Now they're older teens, who spend more money on film than any other age set.

"Our biggest audience was 8- to 10-year-olds when we started all this," says Dan Fellman of Warner Bros., which distributes the pictures.

"They've grown up on the films," Fellman says. "And they haven't lost any of their passion."

Potter has become one of Hollywood's most lucrative franchises by matching the adult themes and intensity of the book series, a strategy that has impressed critics: 84% of them recommended the movie, according to movie review site RottenTomatoes.com.

"We have great source material," Fellman says. "We owe it to fans and J.K. to be as faithful to her great stories as we can be."

No other major film competed with Half-Blood Prince this weekend, though several holdovers performed well. Ice Age: Dawn of the Dinosaurs dipped just 36% from the previous weekend, earning $17.7 million and lifting its total to $152 million.

Transformers: Revenge of the Fallen also chugged along with $13.8 million for $363.9 million overall.

Not so lucky was Brüno, the Borat follow-up by Sacha Baron Cohen. The documentary-style comedy fell 73% from its debut, mustering $8.4 million. The Hangover was fifth with $8.3 million to bring its total to $235.9 million.

Though ticket sales were up 15% from the previous weekend, they plummeted 39% from the same weekend last year. Final figures are due Monday.