Mumbai, May 8 -- Hindustan Zinc Ltd gained for a fifth straight session today. The stock is quoting at Rs 639.2, up 0.42% on the day as on 12:44 IST on the NSE. The benchmark NIFTY is down around 0.67% on the day, quoting at 24164.3. The Sensex is at 77254.26, down 0.76%. Hindustan Zinc Ltd has gained around 14.45% in last one month. Meanwhile, Nifty Metal index of which Hindustan Zinc Ltd is a constituent, has gained around 6.85% in last one month and is currently quoting at 13165.4, down 0.75% on the day. The volume in the stock stood at 22.76 lakh shares today, compared to the daily average of 69.16 lakh shares in last one month. The benchmark May futures contract for the stock is quoting at Rs 638.8, down 0.01% on the day. Hindustan Z...