The document provides a summary of derivative market activity in India for October 20, 2010. It notes that open interest for Nifty futures decreased while open interest for Minifity futures increased. The Nifty October future closed at a premium while the November future also closed at a premium. Implied volatility of at-the-money options increased. Several stocks saw increases and decreases in open interest. The document also provides analysis of bullish and bearish option strategies and reviews open derivative positions.