An excellent article from Michael D. Watkins about the transition from being a manager to becoming a leader, in the Harvard Business Review.
He reviews that point in your career where you move from being a functional manager to having enterprise responsibilities across functions. It takes a number of changes in your approach and Michael makes this clear in a short and concise manner. Read also his books listed below for a more indepth story.
The article can be found here
Michael D. Watkins in a cofounder of Genesis Advisers, a leadership development firm specializing in onboarding and transition acceleration, and a professor at IMD.