Crude palm oil prices tumbled 4 per cent to hit lower circuit at 407.20 rupees per 10 kg in futures trade today after participants off-loaded their positions amid a weak trend overseas and subdued demand at spot markets. The oil to be delivered in November also fell by a similar margin to hit a lower circuit at 409.10 rupees per 10 Kg. Trading sentiment remained bearish largely in line with a weak trend overseas after palm oil futures in Malaysia traded lower as a global economic slowdown hurt demand for the oil and an increase in production in Indonesia and Malaysia.