What is the highest-grossing adaptation of a stephen king novel?

It Chapter 1.

Explanation:

Stephen King is one of the most famous writers of horror, suspense, thriller and even fantasy stories. And most of his famous works had also been made int high grossing movies, some even getting acclaimed awards in the field.

Among the numerous novels written by King, his highest grossing novel adaptation movie is "It : the First Chapter" or even "It - Part 1: The Losers Club". This story is about a terror seven children faced when they were forced to face their own personal demons. The character of It terrorizes the children of Derby, abducting and killing them, even eating them. This horror movie ends in the blood pact among the group of kids to fight It again if he ever returns.

This movie was later followed by It Chapter Two (2019), but did not gain as much as the first series. The first "It" stars Jaeden Lieberher and Bill Skarsgård in the main roles.