On March 7, the copper market suffered one of the biggest price drops for years, losing some 4% in a matter of hours.

This fall was precipitated by large metals hedge funds in China, who recognised that copper prices were out of line with equities.

The funds have been described by some market observers as the largest directional players on the London Metal Exchange.

Metal Bulletin's editor Alex Harrison takes a look at the funds: what they trade, how much they're worth and what gives them the edge over their competitors.

Alex Harrison
Twitter: @alexharrison_mb