On February 1, the Nifty 50 saw volatility on the budget day, reaching resistance at 21,850 before ending with moderate gains. It negated a bearish formation and may fill a downside gap created on January 17 if it surpasses 21,850. It held key moving averages and experts expect a range-bound movement between 21,840 and 21,420. They suggest deploying an Iron Butterfly strategy with a probability.