LOS ANGELES (AP) — Harry Potter continues to work box-office alchemy, turning his latest movie adventure into an overnight blockbuster.

The sixth installment, "Harry Potter and the Half-Blood Prince," took in $79.5 million domestically over opening weekend and $159.7 million since debuting last Wednesday, according to estimates from distributor Warner Bros. yesterday.

The movie also took in $237 million overseas since Wednesday in 54 countries, bringing its worldwide total to $396.7 million.

With some of the best reviews of any "Harry Potter" movie, "Half-Blood Prince" was off to the fastest overall start in franchise history.

The sixth movie about the young wizard came in $20 million ahead of the last movie, "Harry Potter and the Order of the Phoenix," which grossed $139.7 million domestically in its first five days two years ago.

The new film had the second-highest start ever for a movie premiering on Wednesday, trailing the $200 million five-day opening for last month's "Transformers: Revenge of the Fallen."

"Half-Blood Prince" already has surpassed the $157.3 million "Order of the Phoenix" pulled in during its entire first week. By the end of its seventh day Tuesday, "Half-Blood Prince" will be in the $180 million range on its way to becoming the franchise's first $300 million domestic smash since the original movie, 2001's "Harry Potter and the Sorcerer's Stone," said Dan Fellman, Warner head of distribution.

The audience was a bit older for the new movie, with more elder teens turning out to see Harry (Daniel Radcliffe) and pals Hermione (Emma Watson) and Ron (Rupert Grint) as they deal with adult concerns such as heartache, jealousy and romantic triangles.

Fans have grown up with the franchise, from young readers whose parents had to debate whether the early movies might be too intense for their children to see.

"When the first movie came out, they fought to go. The mother was like, well, should I take them, should I not take them?" Fellman said. "Now they're driving themselves to this and going to the midnight show."

Sacha Baron Cohen's mock documentary "Bruno" plummeted after its number one debut the previous weekend. The Universal Pictures comedy fell to fourth-place with $8.4 million, down a whopping 73 percent from its $30.6 million opening.

Crowd-pleasing movies typically dip 50 percent or less in their second weekends. But "Bruno" has had mixed reviews and failed to earn the audience buzz that made a $128 million hit out of Baron Cohen's 2006 comedy "Borat: Cultural Learnings of America for Make Benefit Glorious Nation of Kazakhstan."

After 10 days in release, "Bruno" has climbed to $49.6 million and will finish far below $100 million domestically.

While "Harry Potter" had a healthy start, the overall box office plunged compared to the same weekend last year, when the Batman juggernaut "The Dark Knight" had its record opening weekend of $158.4 million.

The top-12 movies this weekend combined for less than that, taking in $153.9 million, down 39 percent from a year ago.

"We got kind of slaughtered even with the 'Potter' movie, but we knew that was going to happen," said Paul Dergarabedian, box-office analyst for Hollywood.com. "When one movie last year makes more than what the top-12 movies did this year, you're going to have a down weekend."

Estimated ticket sales for Friday through Sunday at US and Canadian theatres, according to Hollywood.com. Final figures will be released today.

1. "Harry Potter and the Half-Blood Prince," $79.5 million.

2. "Ice Age: Dawn of the Dinosaurs," $17.7 million.

3. "Transformers: Revenge of the Fallen," $13.8 million.

4. "Bruno," $8.4 million.

5. "The Hangover," $8.32 million.

6. "The Proposal," $8.3 million.

7. "Public Enemies," $7.6 million.

8. "Up," $3.1 million.

9. "My Sister's Keeper," $2.8 million.

10. "I Love You, Beth Cooper," $2.7 million.