N Chandrasekaran has stepped down as Tata Sons chairman, tendering his resignation on August 12. His resignation comes amid uncertainty over his reappointment as a director of Tata Sons and reported differences within the Tata group. Here is a timeline of Chandrasekaran’s journey at Tata Sons and the key developments leading up to his resignation:2016: Joins Tata Sons boardChandrasekaran joined the board of Tata Sons in October 2016, after spending several years leading Tata Consultancy Services (TCS). January 2017: Takes over as Tata Sons chairmanIn January 2017, Tata Sons announced Chandrasekaran as its new executive chairman. At the same time, the Tata group continued to invest heavily in businesses such as Air India, Tata Electronics and Tata Digital.