BEIJING, Jan. 19 (Xinhua) -- Lock-up shares worth 22.6 billion yuan (3.7 billion U.S. dollars) will become eligible for trade next week in China.

The volume marks a slight rise from the 20.83 billion yuan from Jan. 13 to Jan. 17, according to information from the Shanghai and Shenzhen stock exchanges.

Altogether, 20 listed companies on the two stock exchanges will see their lock-up shares released onto capital markets next 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.

Of all the companies with non-tradable shares becoming tradable next week, Changshu Fengfan Power Equipment Co., Ltd. ranks first with its non-tradable shares worth 3.66 billion yuan.