Bharti Infratel has dipped 4% to Rs 364, its lowest level of the day on the BSE, in otherwise strong market as the stock turned ex-date for buyback of shares. The S&P BSE Sensex was up 1% or 309 points at 26,708. The company has fixed June 16, 2016 as the record date for the purpose of buy-back of equity shares. It will buy back shares worth Rs 2,000 crore on a proportionate basis from the shareholders though tender offer.