Shares of Adani Enterprises tanked 8.70 per cent to settle at Rs 454.30 on the BSE. During the day, it lost 10.57 per cent to touch a low of Rs 445.
At the NSE, it plunged 9.72 per cent to end at Rs 449.75.
The Competition Commission of India's (CCI) ruling has come on a case related to supply and distribution of natural gas by Adani Gas Ltd in Faridabad. Adani Gas is a subsidiary of Adani Enterprises, which is part of diversified Adani Group.
A fine of Rs 25.67 crore has been imposed on Adani Gas for abusing dominant position, the regulator had said in a statement yesterday.
The penalty amount translates to 4 per cent of average of Adani Gas's turnover for the last three financial years.
In the broader market, the Sensex fell by 517.97 points to settle at 25,582.11 points.