Tata Power's scrip lost 3.66 per cent to Rs 85.50 on the BSE.
On the NSE, it was down 3.83 per cent to Rs 85.35.
Tata Power had yesterday reported a consolidated loss of Rs 78 crore for the September quarter as the company was impacted by lower revenues from coal business, among other factors.
The leading power producer had a consolidated profit after tax of Rs 75 crore in the July-September quarter of last fiscal.
Its revenue on a consolidated basis fell to Rs 8,394 crore from Rs 8,765 crore in the year-ago period due to lower realisation by coal companies and lower fuel cost in Mumbai operations, Tata Power had said in a statement.