There is a new runner-up for the title of the world’s biggest company. Soon, there may be a new winner too.

PetroChina, the state-controlled Chinese oil and gas group, this week overtook General Electric to become the world’s second-biggest company by market capitalisation. After it lists on the Shanghai stock exchange, which it is expected to do next month, it could even surpass ExxonMobil to become the world’s most valuable quoted business.