Spot rubber was weak on Monday. RSS 4 slid to Rs 137.00 (137.50) a kg according to traders and the Rubber Board. The grade dropped to Rs 133.00 (133.50) a kg as quoted by the Dealers. The March futures declined to Rs 137.83 (138.43) and April to Rs 141.07 (141.58) per kg while the May futures improved to Rs 143.98 (140.22) per kg on the Indian Commodity Exchange (ICEX). The near month March contracts were down by 0.43 per cent with a volume of 586 lots and total trade value of 807.62 lakhs. RSS 3 (spot) firmed up to Rs 111.12 (110.16) per kg at Bangkok. The February futures improved to Rs 105.01 (101.41), March to Rs 116.05 (114.28) and April to Rs 118.85 (118.31) per kg on the Tokyo Commodity Exchange (TOCOM).