[Stock Index Futures Opening in the Morning Session] The main contract of CSI 300 stock index futures (IF) fell 2.50%, the main contract of SSE 50 stock index futures (IH) fell 1.91%, the main contract of CSI 500 stock index futures (IC) fell 4.00%, and the main contract of CSI 1000 stock index futures (IM) fell 3.61%.