Mahindra BT Investment Co has sold its entire 8.07 per cent stake in IT company Tech Mahindra to US-based communications firm AT&T, it has been reported. The deal cost an estimated $34.5 million.

As per the terms of a 2005 agreement with Tech Mahindra, formerly Mahindra British Telecom, AT&T was granted options over approximately 9.9 million shares. AT&T has since decided to exercise these options.