BEIJING - Lock-up shares worth 17.2 billion yuan ($2.80 billion) will become eligible for trading on China's stock markets this week.

The volume is almost flat from last week but halves the figure for the first week in June.

Shares of 20 companies, five on the Shanghai Stock Exchange and 15 on the Shenzhen Stock Exchange, will become tradeable, according to data from the two bourses.

Most of them have a small volume of lock-up shares coming online, with two exceptions being Zhejiang Kaier New Materials Co Ltd and Anhui Jiangnan Chemical Industry Co Ltd, each of which will have shares worth more than 2 billion yuan eligible for trade.

Under market rules, major shareholders of non-tradable stocks are subject to a lock-up period of one or two years before they are permitted to sell their shares.

Chinese shares have remained bearish in the first half of the year. The benchmark Shanghai Composite Index finished at 2,026.67 on Friday, while the Shenzhen Component Index closed at 7,195.69.