SHANGHAI, May 2 (SMM) –Discounts on spot copper were quoted between negative RMB 80-20/mt in Shanghai in the morning business. Traded prices for standard-quality copper were between RMB 58,420-58,520/mt, and RMB 58,450-58,580/mt for high-quality copper. SHFE copper prices moved lower after a high open, causing the SHFE/LME copper price ratio to slide further. Supply of imported copper continued to decrease as a consequence. Spot copper, especially domestic copper, thus held prices firm, and helped spot copper discounts narrow. Copper futures prices, though, lacked upside momentum during the first trading day following the May Day holiday, so markets kept generally cautious. Downstream producers were not seen to make stocks, largely taking a wait-and-see stance. Optimistic speculators were mainly market participants, keeping overall market transactions muted.