4)PetroChina Co. Ltd.(PTR)

PetroChina Company Limited is a Chinese oil and gas company and is the listed arm of state-owned China National Petroleum Corporation (CNPC), headquartered in Dongcheng District, Beijing. The company is currently Asia's largest oil and gas producer and was China's second biggest oil producer in 2006.Traded in Hong Kong and New York, the mainland enterprise announced its plans to issue stock in Shanghai in November 2007, and subsequently entered the constituent of SSE 50 Index. In the 2020 Forbes Global 2000, PetroChina was ranked as the 32nd-largest public company in the world.

PetroChina was established as a joint stock company with limited liabilities under the Company Law of the People's Republic of China (the PRC) on November 5, 1999, as part of the restructuring of CNPC. In the restructuring, CNPC injected into PetroChina most of the assets and liabilities of CNPC relating to its exploration and production, refining and marketing, chemicals and natural gas businesses.

Although PetroChina is the most profitable company in Asia, this success may be the result of corporate management, but can also be attributed to the near duopoly[failed verification] on the wholesale and retail business of oil products it shares with Sinopec in China.

Because of Sinopec's link to Sudan through parent company China Petrochemical Corporation, several institutional investors such as Harvard and Yale decided, in 2005, to divest from Sinopec. Sudan divestment efforts have continued to be concentrated on PetroChina since then. Fidelity Investments, after pressure from activist groups, also announced in a filing in the US that it had sold 91 per cent of its American Depositary Receipts in PetroChina in the first quarter of 2007.

At the beginning of May 2007, the company announced it had made China's largest oil find in a decade off the country's northeast coast, in an oilfield named Jidong Nanpu oil field in Bohai Bay. In May 2008 these expectations were lowered.

On November 7, 2007, Hang Seng Indexes Company announced that PetroChina would be a Hang Seng Index Constituent Stock, effective December 10, 2007. PetroChina has also come under scrutiny from international organizations for its part in trading with the Sudanese government who continues the ongoing war in Darfur.