2009 was a great year for Star Trek, but maybe not such a great year for parent studio Paramount. The J.J. Abrams' reboot found its way onto the top spot of 2009's "most-pirated" list, according to The Hollywood Reporter. With almost 11 million illegal downloads, that placed Trek just a tad higher than the number two film on the list, Paramount's Transformers: Revenge of the Fallen.
You can't count that 11 million as a loss, as that would assume everyone who downloaded it would've bought a ticket, but that's still an impressive (and damaging) number. The average ticket price for a movie in 2009 is $7.18 (source). If you were to apply that price to 11 million downloads, you'd be looking at a box office take in the neighborhood of $79 million dollars. That's huge.
The number three film on the list, Guy Ritchie's RocknRolla, grossed a middling $26 million in its theatrical run, but if every bootleg download counted as a ticket sold, that would've bolstered the film's take by $64 million.
Personally, I don't think there's a lot of crossover audience between those that download and those that are regular movie-goers, and the area that gets hurt the most by illegal downloading is definitely the home video market (which has seen huge declines in recent years). The studios still seem like they're at a loss on how to stop pirating, and, as technology improves, an effective solution will only become harder to find.