Spot rubber finished firm on Monday. RSS 4 improved to ₹141 (₹140) a kg, according to traders. The grade firmed up to ₹140 (₹139) and ₹137 (₹136) respectively, as reported by the Rubber Board and dealers. The trend was mixed. January futures improved to ₹140.25 (₹137.98), February to ₹146.80 (₹143.79), March to ₹150.50 (₹147.51), April to ₹157.76 (₹153.96) and May to ₹163 (₹159.89) on the National Multi Commodity Exchange. RSS 3 (spot) firmed up to ₹161.72 (₹159.08) a kg at Bangkok. Spot rubber rates (₹/kg): RSS-4: 141 (140); RSS-5: 132 (131); Ungraded: 119 (119); ISNR 20: 129 (128) and Latex (60% drc): 84 (84).