PETROCHINA Co, the world's biggest company by market value, said one billion additional yuan-denominated shares will become tradable next week in Shanghai.

Trading in the so-called A-shares will start on Tuesday, Beijing-based PetroChina said in a statement to Shanghai Stock Exchange yesterday.

Institutional investors holding the company's stock can sell the shares three months after it was listed in Shanghai on November 5, it said.

PetroChina raised 66.8 billion yuan (US$9.3 billion) selling four billion shares in the world's biggest share sale last year.

The stock, which almost tripled on its debut, has lost about half of its value as global markets tumbled.