Sony American depositary receipts at last check were up 2.6% to $71.57.
The deal gives Sony a minority interest in the game development studio and publisher, which is estimated to be valued as high as $17 billion.
The investment "allows Sony and Epic to aim to broaden their collaboration across Sony’s leading portfolio of entertainment assets and technology, and Epic’s social entertainment platform and digital ecosystem to create unique experiences for consumers and creators," the companies said.
"Through our investment, we will explore opportunities for further collaboration with Epic to delight and bring value to consumers and the industry at large, not only in games, but also across the rapidly evolving digital entertainment landscape,” Kenichiro Yoshida, Sony's chairman, president and chief executive, said in a statement.
Tim Sweeney, founder and CEO of Epic, said "Sony and Epic have both built businesses at the intersection of creativity and technology, and we share a vision of real-time 3D social experiences leading to a convergence of gaming, film, and music."
"Together we strive to build an even more open and accessible digital ecosystem for all consumers and content creators alike,” Sweeney said.
Epic said that Fortnite is the world’s largest game with over 350 million accounts and 2.5 billion friend connections.
In May, Epic used a PlayStation 5 demo to show off the capabilities of the next version of its game engine, Unreal Engine 5.
Last month Sony said that it planned to sell a version of the PlayStation 5 that lacks an optical drive.