The document provides a summary of derivative market activity in India for July 27, 2010. Key points include: - Open interest for Nifty and Mini Nifty futures decreased by 4.23% and 4.53% respectively as the market closed at 5418.60. - Nifty July futures closed at a premium while August futures closed at a higher premium. - Total open interest in the market was Rs. 1,70,070cr with stock futures open interest at Rs. 44,921cr. - Notable gainers in open interest included Maruti, Indian Bank, and CESC while losers included Lupin, Allahabad Bank, and APL Apollo Tubes.