SHANGHAI: PetroChina shares plunged on Friday, after the Chinese energy giant posted its first quarterly loss since listing overseas 16 years ago, as it struggled with weak domestic economy and lower international oil prices. PetroChina lost 13.79 billion yuan in the first quarter, reversing from a gain of 6.15 billion yuan for the same period a year ago, it said in a statement to the Hong Kong exchange late Thursday. It was the first quarterly loss by PetroChina since it listed on the bourse in 2000, Bloomberg News reported. PetroChina stock was down 3.89 per cent in Hong Kong by Friday afternoon and fell 1.59 per cent in Shanghai.