As many investors will know, metals prices have suffered a fair drop in recent weeks, driven by a strong US dollar, and copper has not been immune to those losses. Though copper usually performs in tandem with the global economy, supply worries and apprehension over demand from China have taken a hit at prices in recent weeks. The red metal rebounded from a three-month low today after the release of positive manufacturing data from China, but finished flat overall. According to Bloomberg, copper futures for delivery in three months on the London Metal Exchange (LME) lost 0.1 percent and finished at $6,720 per tonne, while futures on the New York COMEX dipped 0.1 percent to finish at $3.035. Those changes came after a boost in prices earlier in the day, when three-month LME copper gained 0.65 percent to reach $6,764. PMI: for better or for worse? According to Reuters, the jump came after an HSBC flash reading on China's Purchasing Managers' Index (PMI) for September returned 50.5, an increase from 50.2 in August. Expectations had been for a drop to 50, so the increase caught most market watchers and investors by surprise — especially since, as the news outlet reported in a separate article, factory employment in China recently touched its lowest level in over five years. The 50-point line marks the boundary between growth and contraction, so it should be good for the red metal that China's economy is growing. However, as Capital Economics' senior commodities analyst, Caroline Bain, told Reuters, the positive PMI also reduces the prospect of economic stimulus from China, balancing out the positive news. "It is good that the Chinese economy isn't collapsing, but a weaker PMI (purchasing managers index) number would have raised the likelihood of further stimulus from China, which would have given a boost to copper," she stated.