Hollywood Reporter points out what was likely a key factor in the decision to postpone Harry Potter and the Half-Blood Prince for half a year.

For a publicly traded company like Warners parent Time Warner, earnings growth is vital. So moving Potter to next summer improves prospects of a decent revenue comparison with Batman-swelled ‘08.

This isn’t just about box office. If Warners releases Potter this fiscal year, it has to market it this fiscal year, which is a whole lotta dinero out of this year’s budget.

Analysts including Pali Capital’s Rich Greenfield noted that the film’s original November slotting would have weighted the fourth quarter with heavy marketing costs, while “Dark Knight” already ensures a healthy revenue haul for the studio in 2008.

So, if The Dark Knight hadn’t have been so darn successful, they might have had to release Harry Potter this year to make up the difference so, in a way, this is all Batman’s fault.