US-based operator AT&T has sold its entire 8.07 per cent stake in software service provider Tech Mahindra. It has sold 7 per cent of the stake in a deal worth Rs 6.6 billion and another 1 per cent in the open market. The bulk of the stake has been bought by the Life Insurance Corporation (LIC), which already holds a 7.4 per cent share in Tech Mahindra. LIC now has 12-14 per cent ownership in the company. Citigroup was the adviser to AT&T in the transaction. AT&T bought the stake in March 2010 by exercising a purchase option (at around Rs 162 per share). The US company could exercise the option since it had fulfilled certain revenue targets in terms of outsourcing contracts to Tech Mahindra.