The Marvel superhero pic tumbled 66 percent in its sophomore outing domestically, compared to a 53 percent drop for DC's 'Superman.'

First Steps" held firm at the top of the U.K. and Ireland box office for a second weekend, adding £3 million ($4.1 million) and bringing its total to £15.3 million ($20.4 million), according to Comscore.

Captain America: Brave New World and Thunderbolts also saw so-so box office returns, with the former earning $415 million globally and the latter taking home $386 million. The lowest-grossing Marvel movie of all time is The Marvels, which just broke even at $206 million globally, with 2012's The Incredible Hulk coming in second at $265 million.