Mazagon Dock Shipbuilders has become the 18th Indian PSU to be granted 'Navratna' status by the Department of Public Enterprises, the company said in an exchange filing on Tuesday. It can now invest up to ₹1,000 crore without needing government's approval. It can also invest up to 30% of its net worth in a year, but not over ₹1,000 crore.