Chicago: ExxonMobil Corp. regained the mantle as the world's biggest company by market value, overtaking PetroChina Co., whose shares have slumped 58 per cent since its listing in Shanghai.

PetroChina dropped for a fifth day, falling 2.5 per cent to 18.54 yuan by the close, reducing its market capitalisation to $453.1 billion. The Chinese company's Hong Kong-traded stock dropped 1.4 per cent to HK$9.68. ExxonMobil was valued at $455.8 billion yesterday after rising 13 per cent in the past year on record energy prices.

PetroChina, an eight-year-old creation of the Chinese government, in November overtook ExxonMobil, which traces it roots to the 1880s and John D. Rockefeller's Standard Oil Trust, when the Chinese company's market value surged to $1 trillion. Since then, PetroChina lost more than half its worth as $100-a- barrel oil and rising drilling costs squeezed profits.

"PetroChina just doesn't show up in terms of reaping any kind of excess reward for the sort of risk involved in investing in them," said Phillip Mitteldorf, a portfolio manager who helps oversee $5 billion at Navellier & Associates Inc. in Reno, Nevada. "We won't even look at them." ExxonMobil raked in $40.6 billion in profit last year, the biggest ever for a US company.

ExxonMobil's 2007 sales of $358.6 billion exceeded the gross national products of every nation on Earth except the US, Japan, Germany and 17 others.

Five-month reign

PetroChina's five-month reign as the world's most-valuable corporation began after its stock price tripled in the first day of Shanghai trading after an offering of four billion shares. ExxonMobil declined about three per cent since then.

The value of Chinese stocks fell 25 per cent this year to $3.36 trillion after more than tripling in 2007. The Standard & Poor's 500 Index, by comparison, this year has fallen 7.9 per cent.

ExxonMobil's refining business, the world's largest, had profit of $184 million a week in 2007. The company sells 80 per cent of the fuel it produces in markets where price controls are less restrictive or non-existent.

Cause: Price curbs hurt firm

Investors who bought PetroChina stock on the expectation that rising energy demand in China's expanding economy would boost the company's refining profit have been disappointed, said James Halloran, an analyst at Cleveland-based National City Private Client Group, which manages $35 billion.

PetroChina's refineries lost $54 million a week last year because of government price controls that prevented the company from passing higher oil costs. The shares dropped to a 10-month low in Hong Kong when those results were announced on March 20.