Benchmark indices ended with marginal gains in the volatile session on January 13 with buying seen in the metal and pharma names.At close, the Sensex was up 85.26 points or 0.14% at 61,235.30, and the Nifty was up 45.50 points or 0.25% at 18,257.80. About 1630 shares have advanced, 1609 shares declined, and 62 shares are unchanged. Tata Steel, JSW Steel, Sun Pharma, Coal India and UPL were the top Nifty gainers. Losers were Wipro, Asian Paints, HDFC Bank, Kotak Mahindra Bank and IndusInd Bank.