China Tightens Grip on Stocks With Net Sale Ban at Open, Close

China has banned major institutional investors from reducing equity holdings at the open and close of each trading day, part of the government’s most forceful attempt yet to prop up the nation’s $8.6 trillion stock market.

The order from China’s securities watchdog was recently delivered to major asset managers and the proprietary trading desks of brokerages, according to people familiar with the matter, who asked not to be named because they weren’t authorized to speak publicly. The China Securities Regulatory Commission, led by newly appointed Chairman Wu Qing, has also created a task force with the nation’s stock exchanges ...