BEIJING - A total of 23 companies, including China National Nuclear Power, will start taking IPO subscriptions in the coming week that will constrain liquidity in the increasingly volatile stock market.

Specifically, five firms plan to become listed on the Shanghai Stock Exchange, seven on the SME board of the Shenzhen Stock Exchange, and eleven on the ChiNext-board, a Nasdaq-style board for growth enterprises.

The subscriptions may lock up around 7.2 trillion yuan in the market ($118 billion), according to Guotai Junan Securities. Minsheng Securities estimated the volume to be over 8 trillion yuan.

The new influx of shares has weighed on market sentiment in recent trading days. The benchmark Shanghai Composite Index plummeted 6.5 percent on Thursday to finish at 4,620.27 points, while the Shenzhen Component Index plunged 6.19 percent to close at 15,912.95 points.