SHANGHAI -- Shares of CITIC Heavy Industries Co opened up 0.4 percent on their first day of trading on Friday, as it staged a tepid debut amid?economic uncertainty and a sluggish market that weighed on China's biggest initial public offering this year.

CITIC Heavy shares opened at 4.69 yuan, compared with its IPO price of 4.67 yuan.

The 3.2 billion yuan ($503 million) IPO is the first major offering by a Chinese company after regulators unveiled a series of rules aimed at pushing down IPO prices and curb speculative trading in newly-listed stocks.

CITIC Heavy had planned to raise 6 billion yuan, but later slashed its fundraising target by a third due to market sluggishness. China's main stock index has been flat this year after last year's drop.