Hindustan Zinc began life as a public sector entity in 1966. The government sold 26% of their shares to Sterilite industries owned by Vedanta two decades ago. Since then, Hindustan's rise has been swift and it is now the second largest miner of zinc led in the world. S&P Global Ratings raised questions about how financially healthy the company was. If not, S&P would have to downgrade Vedanta's debt rating.