Benchmark indices started the week on a positive note driven by banks, auto, metals and select technology stocks. Nagaraj Shetti, Senior Technical & Derivative Analyst, HDFC Securities said the underlying short term trend of Nifty continues to be positive. Nifty closed at 11,690.35 on April 15. According to the Pivot charts, the key support level is placed at 11,657.47, followed by 11,624.63. If the index starts moving upward, key resistance levels to watch out are 11,713.87 and 11,737.43. Maximum Call open interest of 26.29 lakh contracts was seen at the 12,000 strike price. This was followed by 11,800 strike price.