The Walt Disney Co. said Tuesday it was buying longtime partner Pixar Animation Studios Inc. for $7.4 billion in a deal that could restore Disney’s clout in animation while vaulting Pixar CEO Steve Jobs into a powerful role at the media conglomerate.

Disney will buy the maker of the blockbuster films “Toy Story and “Finding Nemo” in an all-stock transaction that makes Jobs Disney’s largest shareholder. Jobs, who controls more than half of Pixar’s stock and also leads Apple Computer Inc., will also join Disney’s board.