The days when investors could invest in base metals and goldmining companies and watch the share prices rise with little or no change in their outlook seem long ago.

But they ended only in the past five months. For the past three years, prices of key commodities like copper and gold have shot up. Copper has almost tripled and gold has risen about 60 per cent over this period, benefiting marginal operators such as miners and smaller producers the most. It is only since May that concerns about continuing economic growth have stunted their prices.