The stock plunged 6.13 per cent to Rs 142.30 on BSE.
On NSE, the stock dropped 6.35 per cent to Rs 142.25.
The stock was the top loser on NSE's 50-share Nifty.
Idea Cellular, India's third-largest telecom operator by subscribers, on Wednesday reported a 7 per cent increase in net profit at Rs 809.26 crore for the July-September quarter, helped by non-voice revenue growth.
The company, however, witnessed a decline in voice usage and pressure on mobile data.
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Idea, part of the Aditya Birla conglomerate, had reported a net profit of Rs 755.88 crore for the second quarter of the last fiscal.
It said voice minutes usage declined to 189.5 billion for the quarter under review compared with 195.8 billion in the preceding three months (April-June of 2015-16).
On a sequential basis, Idea's net profit declined to Rs 809.3 crore in the reported period from Rs 930.8 crore the previous quarter while total revenue was down to Rs 8,689.1 crore from Rs 8,798.3 crore.
Stock markets were closed yesterday for Dussehra.