Also, when people have short positions in the equity markets they get margin calls and are forced to close out their positions by buying stock when the market rises. This would be a similar process that roymurdock mentioned but to the upside. It's called a "short squeeze."
https://en.wikipedia.org/wiki/Trading_curb#China
"If the CSI 300 Index rises or falls by 5%..."
Also, when people have short positions in the equity markets they get margin calls and are forced to close out their positions by buying stock when the market rises. This would be a similar process that roymurdock mentioned but to the upside. It's called a "short squeeze."
https://en.wikipedia.org/wiki/Short_squeeze