Untraded shares or refer to the shares of listed companies that are not allowed to be released by some of the investors within the lockup period. Since the split-share structure reform  was launched by the State Council of the People's Republic of China

State Council of the People's Republic of China

The State Council of the People's Republic of China , which is largely synonymous with the Central People's Government after 1954, is the chief administrative authority of the People's Republic of China. It is chaired by the Premier and includes the heads of each governmental department and agency...

 in 2005, some of the investors were not allowed to release their shares of the listed state-owned enterprises until the lockup period expired, so as to sustain the overall stock market. After the lockup period expires, the investors can choose to sell the shares and this may cause negative impacts to stock market

Stock market

A stock market or equity market is a public entity for the trading of company stock and derivatives at an agreed price; these are securities listed on a stock exchange as well as those only traded privately.The size of the world stock market was estimated at about $36.6 trillion...

from the selling pressure.