Cochin Shipyard shares tumbled despite 11.7% revenue growth in the September quarter, as net profit halved and Ebitda margin contracted to 4.1% from 6.6%. The bigger concern came from its shipbuilding business, which swung to an operating loss of Rs 6.1 crore from a profit of Rs 149.7 crore a year earlier. Meanwhile, the ship repair business delivered stronger growth. What went wrong with Cochin Shipyard's core business, and why are investors reacting so sharply? Maumita Mitra explains the key factors weighing on the stock.