METALS, a normally volatile lot, have been even wilder during the past few weeks.

Any hint of where prices are headed - up, down or sideways and for how long - will be of particular interest when BHP Billiton, the world's largest miner, reports its profit results for the latest financial year on Wednesday.

Prices for key commodities, including iron ore, copper and coal have risen between 22 per cent and 52 per cent in the first half of the year, compared with the same period a year earlier. Most mining companies had been predicting that prices will stabilise at current high levels, making for a strong second half.

Despite escalated concerns about the European sovereign-debt problems and potential double-dip recession in the US, the outlook remains relatively unchanged due to two basic fundamentals: supply is constrained and global demand, while moderating, is still growing.