Guar gum prices on Monday fell Rs.389 to Rs.9,338 per five quintal in futures market as traders offloaded their holdings in line with weak trend at spot market. On the National Commodity and Derivatives Exchange, guar gum for September delivery fell by Rs.389, or 4 per cent, to Rs.9,338 per five quintal in 635 lots. Marketmen said slackness in demand in the spot market and increased supplies from growing regions put pressure on guar gum prices.