A rising star at Time magazine has resigned to pursue outside writing activities.

Romesh Ratnesar was deputy managing editor under the magazine’s top brass, Managing Editor Rick Stengel, and ran most day-to-day operations of the print magazine.

Sources say Ratnesar had indicated he was going to leave last fall, but then Josh Tyrangiel, the other deputy managing editor, resigned to become editor-in-chief of BusinessWeek. Both editors were in their mid-30s.

“They were both being groomed to be future editors of Time,” one source said. “It’s a tremendous loss.”