Shares of Tata Consultancy Services (TCS) slipped 0.59% to close at Rs 3,508.95 in the previous trading session. The stock will trade ex-buyback from today. The board of directors of TCS approved a proposal to buy back up to 4,09,63,855 equity shares of the company for an aggregate amount not exceeding Rs 17,000 crore, representing 1.12 per cent, of the total paid-up equity share capital, at Rs 4,150 apiece.