Just because you generate (lets use the Serenity example) 38.8 million in theatre sales world wide on a production budget of 39 million dollars. It will earn (in the US it really can vary overseas) only around 55% (now that can vary for films that have the ability to get a higher upfront rate, I can't see Serenity or X-Files being able to do so, though X-Files would have a better shot by far then Serenity) of that for the studio (and thats assuming the studio doesn't share distribution with another for either US or overseas ticket sales). And the 10 million marketing figure most likely refers to only US marketing (unknown if that includes the print cost, some times yes sometimes no). It is exceptional rare that world wide marketing numbers are released (they are in the same place as world wide dvd sales, rentals and tv rights that studios seem to never have open accounting practices with). So lets just pretend that the 10 million is both marketing and print cost (quite possible) and that it is both US and Overseas cost (highly doubtful). That means it full cost was 49 (and again this is highly suspect). At 49 million Serenity to break even (at the theaters) would need to generate roughly nearly 90 million dollars in ticket sales. Basically its theater run covered at very best half of all its cost. It would then fall to its dvd sales/rentals, tv rights, ect to generate the remaining. Now again the X-files in in better shape (though again in the industries eyes and currently the studios its a bomb) with a 30 million budget and most likely an equally low US marketing campaign. It will need to generate less total revenue. With it already exceeding the overseas total of Serenity and with several major markets left (which will take months to hit). X-files (working under the same assumptions of world wide marketing and print costs) will come much closer to breaking even solely off of its theatrical run.