Here's an exerpt from the Marvel Studios
page on Wikipedia. It reads like, to me anyways, it was more like an agreement to provide loans, as needed, up to a certain monitary value, for a certain amount of movies, over a specified time period, lol. It's not like they got $525 Mill on day one and had to start paying interest, lol!!
In 2004, David Maisel was hired as chief operating officer of Marvel Studio as he had a plan for the Studios to self-finance movies. Marvel entered into a non-recourse financing structure with Merrill Lynch Commercial Finance Corp. that is collateralized by certain movie rights to a total of 10 characters from Marvel's vast vault. Marvel gets $525 million to make a maximum of 10 movies based on the company's properties over eight years, according to the parameters of the original deal with Paramount Pictures in September 2004. Those characters were: Ant-Man, The Avengers, Black Panther, Captain America, Cloak & Dagger, Doctor Strange, Hawkeye, Nick Fury, Power Pack, Shang-Chi. Ambac insurance company insured the movies would succeed or they would pay the interest payment on the debt and get the movie rights collateral. In October 2005, Michael Helfant joined the Studio as President and Chief Operating Officer. In November 2005, Marvel gained the film rights to Iron Man from New Line Cinema. Marvel revealed that it has regained the film rights to The Incredible Hulk in 2006. April 2006 Paramount Pictures acquired the rights to Thor from Sony. That year the film was announced to be a Marvel Studios production. Lions Gate Entertainment subsequently dropped the Black Widow motion picture project it had since 2004 giving the rights back to Marvel.