"Going forward, 21,000 is likely to act as a crucial level for the Nifty, as call writers have built their maximum positions at that strike price. A resumption of the current uptrend might be seen above 21,000, with the potential to reach 21,550. On the lower end, put writers have built significant positions at 20,900 and 20,800; below these levels, profit booking might increase," said Rupak De, Senior Technical Analyst, LKP Securities