Zinc prices on Monday fell 0.42 per cent to Rs 257.80 per kilogram in the futures trade as speculators reduced their exposure, tracking negative cues from the spot market. On the Multi Commodity Exchange, zinc contracts for August delivery traded Rs 1.10 or 0.42 per cent lower at Rs 257.80 per kg in 942 lots. Analysts said trimming of positions by participants owing to slackened demand from consuming industries in the physical market mainly weighed on zinc prices