Here's how it usually works with a blockbuster. It'll have a big opening weekend, then drop off about 40 percent the next weekend, then lose 40 percent from that the next weekend, and so on. Diminishing returns. Everything's front-loaded nowadays: huge opening, then a quick fall-off. This is how it's been for the last decade or so, and the pattern has been remarkably consistent regardless of the film's reviews, marketing, or quality.

Some examples: The Lord of the Rings: The Return of the King made $72 million its first weekend; then $50 million; $28 million; $14 million, $10 million, $6 million, etc. (All figures courtesy of Box Office Mojo and refer to U.S. grosses.) Spider-Man went $114 million, $71, $45, $28, $14, $10, $7, etc. Transformers: Revenge of the Fallen was $108 million, $42, $24, $13, $8, $4, $3, etc. The only thing that varies significantly is how big a drop-off there is from the first weekend to the second weekend. That's where overwhelmingly negative reviews or bad word of mouth plays a part. But even for beloved films, there is SOME loss of audience from week to week. Studio executives are thrilled when something loses less than 50 percent the second week.

But not with Avatar. Avatar opened to $77 million. By the usual standards, it would have been expected to make about $45 million the next weekend. Instead, it made $75 million. This past weekend, its third, it made $68 million. The previous record for a movie's third weekend was $45 million, set by Spider-Man. To still be making this kind of money at week three is unheard of. Why is this happening? Some theories, after the jump.