Spot rubber made sharp gains amidst acute short supplies on Thursday. RSS 4 flared up to ₹140 (₹135) a kg, according to traders and the Rubber Board. The grade improved to ₹139 (₹135) and ₹136 (₹132) respectively, according to the Rubber Board and dealers. May futures firmed up to ₹147 (₹142.50), June to ₹146.69 (₹142.64) and July to ₹145.50 (₹143.08) on the National Multi Commodity Exchange. RSS 3 (spot) quoted higher at ₹118.76 (₹116.98) at Bangkok. April futures closed at ¥198 (₹119.77) on the Tokyo Commodity Exchange. Spot rubber rates (₹/kg): RSS-4: 140 (135); RSS-5: 137 (133); Ungraded: 128(126); ISNR 20: 126 (124) and Latex (60% drc): 111 (109).