Shares in Tata Power Ltd fall 1.7 percent after ratings agency Moody's Investors Service changed its ratings outlook to "negative" from "stable."
Moody's cited "material covenant breaches on bank debt" associated with Tata Power's Gujarat-based Mundra Ultra Mega Power Project.
Moody's adds that the waivers from banks against the covenant breaches secured by the Tata Power unit in charge of the project expired on June 30.
The Mundra Ultra Mega Power Project, an imported coal 4GW power project, is a significant investment for Tata Power as it increases its generation capacity by almost 50 percent, Moody's adds.
Officials at Tata Power were not immediately reachable for comments.