Indian Rayon, a part of the Aditya Birla Group, has acquired a 16.45 per cent stake in Idea Cellular for $150 million. At this rate, the equity value per subscriber works out to about Rs 6,829. The deal raises Indian Rayon's stake in Idea to 20.74 per cent and the Aditya Birla Group's stake to 50.15 per cent. As of August 2005, Idea, which operates in eight circles, had a 9.2 per cent market share with 5.88 million subscribers.