China stocks ride roller coaster on Tuesday as investors look for bottom
* Chinese stocks volatile despite regulatory efforts to calm market
* CSI300 up 2 pct, SSEC flat, after both plunged in early trade
* Unwinding leverage destabilising market
By Pete Sweeney and Samuel Shen
SHANGHAI, June 30 (Reuters) - China stocks plummeted and then rallied again in a highly volatile session on Tuesday, shrugging off regulatory attempts to pacify a tumbling market as rumours swirled about backdoor interventions from Beijing.
Chinese equity markets have fallen more 20 percent from their peak in mid-June, with the Shanghai Composite Index punching through a psychological support level on Monday at 4,000 points, which Bank of America Merrill Lynch analysts warned was a "risk zone" that could trigger more conservative margin traders to eject from their positions.
The CSI300 index rose 2 percent on Tuesday to 4,275.09 points at the end of the morning session, while the Shanghai Composite (SSEC) was unchanged at 4,052.47 points.
China CSI300 stock index futures for July rose 7 percent, to 4,340, which was 64.91 points above the current value of the underlying index.
Tuesday's see-saw trading followed a brutal Monday session in which primary indexes swung wildly, with the SSEC swinging 10 percentage points between its highest and lowest points - its most volatile day in 10 years - to end down more than 3 percent. Continuación...