Commodity prices to see broad-based declines

The broad-based declines in commodity prices in recent weeks hark back to the weakness in Q4 14-Q1 15. Whereas, macroeconomic risks, particularly out of China could limit upside demand surprises, supply surprises appear largely to have been on the upside across most commodity markets. 

For instance in the oil market, several OPEC countries, such as Iran, Iraq and Libya, have the ability to surprise the market with higher-than expected production over the next two years. 

"The build-up in production and shipping capacity in the metals markets over the past few years implies that global supply is likely to remain ample for some time to come, dampening potential price increases", says Barclays.