SHANGHAI - Shares in PetroChina Company Limited, China's largest oil and gas producer, opened Monday at 48.6 yuan on their first day of trade in the mainland A share market, up 191 percent from their IPO price of 16.7 yuan.

The price made PetroChina the world's largest listed company by market capitalization. The previous biggest, Exxon Mobil, was valued at US$ 487.7 billion according to last Friday's share price.

"Returning to the mainland's capital market has been our long-cherished wish," said Jiang Jiemin, president of PetroChina's parent China National Petroleum Corporation (CNPC), "the mainland offering will give domestic investors opportunities to share the outcome of PetroChina's fast growth and help expand the company's business in the mainland," he added.

The share price dropped to 43.65 yuan at the end of morning session with the bench mark Shanghai Component Index dipping 1.42 percent to 5695.57 points as the offerings of the oil giant have incurred concerns of strained funds and wobbles in the stock market.

Many institutional investors said the opening price had reached their upper expectation value.

By A-share listing, the company wanted to increase the crude oil production to match its refining capacity, said Zheng Yi, an analyst with Guangfa Securities.

PetroChina raised 66.8 billion yuan (US$8.9 billion) in Shanghai by selling 4 billion A shares, or 2.18 percent of its expanded share capital, in the world's biggest initial public offer (IPO) so far this year.

According to the company's prospectus, it will use 6.84 billion yuan and 5.93 billion yuan respectively to boost production capacity at its Changqing and Daqing oil fields. A total of 1.5 billion yuan will be used to build production facilities at Jidong field, the country's largest.

It also planned to invest 17.5 billion yuan to upgrade its Dushanzi oil refinery and ethylene facilities and six billion yuan in expanding an ethylene plant in Daqing, in northeast China.

Apart from the 4 billion A-shares issued in the public offering, the CNPC holds the rest of the 158 billion A shares, 86.29 percent of the total. It has 21 billion H Shares.

The PetroChina IPO surpassed the 66.58 billion yuan (US$8.88 billion) achieved by China Shenhua Energy Company, the country's largest coal producer, earlier last month.

On news of the large listing, China's major stock index dropped 2.31 percent on November 2, also the last trading day before the opening of PetroChina in the mainland A share market.

Chinese shares even slumped nearly 5 percent on October 25, the same day as subscriptions for PetroChina A shares began.

The company is the first of the country's three petrochemical giants including Sinopec and the China National Offshore Oil Corp. (CNOOC) to get listed on overseas stock market.

PetroChina began trading in Hong Kong and its American Depository Receipts were listed on the New York Stock Exchange in 2000. Its Hong Kong share price was 19.60 HK dollars last Friday.

Citic Securities Co., UBS Securities Co. and China International Capital Corp. are the main underwriters of the issue.