PetroChina matches Exxon as Most Valuable Company

    By Bloomberg News          PetroChina Co. briefly overtook Exxon Mobil Corp. as the world’s most valuable company after China’s stimulus plan caused a surge in the nation’s stocks this year.     State-controlled PetroChina’s Shanghai-traded shares rose as much as 3 percent to 13.25 yuan today for a market value exceeding $336 billion, surpassing...