The index failed to sustain above 21500 which indicates a lack of buyers. The index also closed below the lower end of the trend channel, a 125 point discount in Futures and a bearish engulfing pattern on the daily chart (on 24th June, last week) signal a heavy correction in the coming days.
On gap down, the levels to short would be at 21200 for a target of up to 20900. If 20900 is breached, the index may fall further down to 20500 -20000.
On gap up/flat opening, a strong buying spree in the first hour should confirm a continuation of the uptrend until 22400. The bullish trend should hold true even if the index goes flat throughout the day but closes above 21600.