As its name suggests, PetroChina Company Ltd is the listed arm of state-owned China National Petroleum Corporation (CNPC). It is China's biggest oil producer, and is listed in Hong Kong, New York, and Shanghai.

PetroChina surges on Buffett spree

PetroChina's shares surged 3.509 per cent yesterday after news that billionaire investor Warren Buffett's New York-listed Berkshire Hathaway had spent HK$1 billion to boost its stake from 0.9 per cent to 1.3 per cent in the company between April 17 and last Thursday.