In the mid-1990s, Marvel was experiencing financial difficulties and looked to sell film rights to several of its comic book characters. They offered the rights to many characters to Sony, but Sony only saw Spider-Man as a valuable property and chose to buy the rights exclusively for that character. At the time, superheroes like Iron Man and Thor were not as popular, and Sony believed Spider-Man alone was worth the investment. Marvel later benefitted from retaining the rights to its other heroes, leading to the creation of the highly successful Marvel Cinematic Universe.