What is the climax of the story Rocking Horse Winner?

The climax occues when Paul's mother gets home and senses that something is off. When she opens the door to his room, she finds him rocking on his horse in a mad frenzy and yelling the name of the horse who will win at the Derby. Paul collapses, his mother takes him into her arms, and Uncle Oscar bets on the horse and makes a large sum of money.