'Serenity' was released at a time when cinema attendance was very flat, especially in America. A lot of films under-performed during this period.
The gross from American box office receipts was approximately $25.5 million. The gross generated in the rest of the world was approximately $13.3 million, making a total gross of $38.8 million.
The production budget was $39 million. This does not include the cost of marketing and distribution. I haven't seen official figures for this but I believe the spend on marketing and distribution in America was something approaching $25 million. I have no idea how much was spent elsewhere.
As a very imprecise rule of thumb, it is said a Hollywood film needs to generate twice its production budget from the domestic box office gross in order to break even. In other words, Universal would have been looking for an American box office gross of at least $78 million. It should be remembered that the production company will only receive about 40% of the gross.
These days, profits are largely derived from DVD revenue and pay-per-view TV. It is likely that 'Serenity' will perform quite well on DVD. However, because of the comparatively poor box office showing it would have to produce exceptionally good results for there to be any realistic chance of a sequel and that is extremely unlikely to happen.
'Firefly' / 'Serenity' has an exceptionally loyal and vocal fanbase that is very active on-line. This tends to give a false impression that the fanbase is a lot bigger than it actually is. Universal took a chance when it bankrolled the film and the promotion was very much geared towards creating grass-roots "word-of-mouth". The fans were tireless in their efforts to promote the film and spread the word but at the end of the day it simply failed to attract a wider audience.
'Serenity' received a lot of very good reviews and is widely considered to be one of the best films of 2005. However, in commercial terms it proved to be a disappointment. Unfortunately, these things happen.
To give a comparison, the figures for 'The Grudge' are as follows:
Production budget: $10 million
Domestic marketing and distribution spend: $40 million (approximate)
American box office gross: $110.3 million
Oversees box office gross: $76.5 million (Total: $186.8 million)
Domestic DVD revenue (Feb-Jul 2005): $48 million
(Quoted as $80 million to date, but this is an approximate figure)