Tata Sons Interim Chairman Ratan N. Tata on Tuesday urged group companies to "act as leaders in their respective markets and enhance returns to shareholders"."The companies must focus on their market position vis-A-vis competition, and not compare themselves to their own past. The drive must be on leadership rather than to follow it," Tata said, speaking to the group companies' managing directors and senior corporate leaders.This is the first reaction from Tata a day after he was named as Tata Sons Interim Chairman in the wake of dizzying developments leading to the removal of Cyrus P. Mistry as Chairman.