In　April　2015,　two　index　futures,　IH　and　IC,　respectively　underlying　big　blue　chip　and　small-medium　stock　indexes,　were　launched　in　China.　However,　because　of　a　market　crash,　they　came　under　strict　control　four　months　later.　Using　a　panel-data　evaluation　approach,　this　paper　examines　how　the　introduction　of　IH　and　IC　affect　the　volatility　of　their　corresponding　stocks.　Results　show　that　IH　significantly　reduces　spot　volatility　before　(after)　a　crash,　but　its　function　is　significantly　weakened　during　a　crash.　IC　always　fails　to　stabilize　the　spot　market　and　even　largely　magnifies　volatility　during　(after)　a　crash.　Such　different　intervention　effects　on　the　two　spot　markets　result　mainly　from　the　different　levels　of　speculation　on　them.　©　2018　World　Scientific　Publishing　Co.