Air China shares were expected to slump when they began trading Friday, the South China Morning Post reported. The airline was forced to scale back its initial public offering by 39%, from US$1 billion to US$577 million, on the back of investor concern over earnings prospects. Analysts predicted this negativity would persist, sending Air China's stock below its opening day offer price. Investors' main worry is the rocketing price of oil and its knock-on effect on air fuel costs. Spending on oil made up 39% of Air China's costs in 2005 compared to 33% in 2004 as the average price of its fuel rose 29% year-on-year.