By Neil Smith
Entertainment reporter, BBC News
The sixth instalment in the hugely successful Harry Potter film franchise will now open in July 2009, eight months later than originally planned.
According to Warner Bros, the decision was made to ensure the studio has a major "tent pole" release next summer.
Harry Potter and the Half-Blood Prince was due to open on 21 November
Studio president Alan Horn also cited the recent Hollywood writers' strike and the effect it had on movies that were to have opened around that time.
The BBC News website spoke to industry experts about some of the other factors which may have influenced Warners' decision.
THE DARK KNIGHT
Batman film The Dark Knight, released last month, is now the most successful Warner Bros title ever at the North American box office.
Factor in its worldwide grosses and its overall takings are north of $700 million - more than enough to make its shareholders happy.
"Warner Bros doesn't need anything else this year," agrees Helen O'Hara of Empire magazine. "Next year is going to be much tougher though.
"The people who deal with release dates are not film-makers; they're worried about the bottom line.
"And the bottom line is they could do with a big film next year more than in November."
QUANTUM OF SOLACE
Had Harry Potter and the Half-Blood Prince opened on 21 November as originally scheduled, it would have entered a marketplace dominated by the next James Bond film, Quantum of Solace.
Does moving the former to summer 2009 avoid a potentially damaging competition for audiences?
Quantum of Solace starring Daniel Craig opens on 31 October in the UK
"I don't think there's a great overlap in the audiences for Bond and Potter," says Jamie Graham of Total Film magazine.
"They're different films aimed at different markets, so I don't see them as competitors or rivals."
One thing they might have been competing for, however, is cinema screens.
"You want to put your biggest releases on as many screens as possible," agrees Graham.
"If there is a scenario where they're being hogged by a film that is lingering around, why not wait?"
HARRY POTTER 7
To date, the Potter franchise has grossed an astonishing $1.4 billion worldwide. Like all good things, though, it will eventually come to an end.
Warner Bros has already extended its lifespan by dividing JK Rowling's seventh and final book, Harry Potter and the Deathly Hallows, into two separate movies.
Could the decision to put back the Half-Blood Prince release date form part of a strategy to ensure this golden goose keeps laying?
O'Hara is not so sure. "I don't think they're trying to eke out the cash cow longer," she told the BBC News website.
"Eight months won't make much difference overall in terms of the Harry Potter franchise."
Hollywood is still feeling the impact of the three-month US writers' strike, which halted film production and put several projects in so-called "turnaround".
With the possibility of an even more damaging actors' strike looming larger by the day, it surely behoves studios to stockpile hits to tide them over the rainy days to come.
The writers' strike brought Hollywood to a standstill earlier this year
"That's just good business sense," says Graham.
"There's a worrying lack of product next year because of the writers' strike, and an actors' strike could create another gap further down the line.
"It makes sense to take your film and plonk it down right in the spot where it papers over the cracks."