American multinational Citigroup on Monday offloaded private sector lender HDFC Bank's shares worth Rs 275 crore through an open market transaction. Citigroup, through its arm Citigroup Global Markets Mauritius, sold 15,79,953 shares of HDFC Bank, as per the block deal data available on the BSE. The shares were disposed of at an average price of Rs 1,742.6 apiece, taking the transaction value to Rs 275.32 crore. Ghisallo Master Fund LP acquired the shares of Mumbai-headquartered HDFC Bank at the same price. Shares of HDFC Bank fell 0.48 per cent to close at Rs 1,734.30 per piece on the BSE. On October 19, HDFC Bank reported a 6 per cent increase in the September quarter net profit to Rs 17,825.91 crore on a consolidated basis. On a standalone basis, the largest private sector lender's post-tax net profit grew to Rs 16,820.97 crore during the reporting period against Rs 15,976.11 crore in the year-ago period. The company's core net interest income grew 10 per cent to Rs 30,010 crore on the back of a 7 per cent increase in gross advances and the margins being stable at 3.46 per cent.