(Reuters) - Starbucks ( SBUX ) said on Tuesday that Chipotle Mexican Grill's head, Brian Niccol, will replace Chairman and Chief Executive Officer Laxman Narasimhan.

The coffee chain has been under pressure from activist investor Elliott Investment Management, which owns a sizable stake and has been pushing it to improve its performance and stock price.

Narasimhan, who was appointed as the company's head in September 2022, is stepping down from his role as CEO and as a member of the board with immediate effect.

Starbucks ( SBUX ) said Niccol will start in his new role on Sept. 9 and the coffee chain's CFO, Rachel Ruggeri, will serve as interim CEO until then.

Chipotle said its board had appointed Chief Operating Officer Scott Boatwright as interim CEO.

Shares of Starbucks ( SBUX ) were up 10% in premarket trading while Chipotle's stock was down 8%.

(Reporting by Granth Vanaik in Bengaluru; Editing by Alan Barona and Sriraj Kalluvila)