BEIJING - Lock-up shares worth 20.83 billion yuan ($3.41 billion) will become eligible for trade this week on the Chinese mainland.

The volume is less than half of the 50 billion yuan in shares that became eligible between Jan 6 and 10, according to information from the Shanghai and Shenzhen stock exchanges.

Altogether 25 listed companies on the two stock exchanges will see lock-up shares released to capital markets this week.

Under the mainland's market rules, major shareholders of non-tradable stocks are subject to one or two years of lock-up before they are permitted to trade.

Sinovel Wind Group Co Ltd, a leading wind turbine producer, will see shares worth about 7.24 billion yuan become available - the most of any company this week.