The iron ore market is not behaving rationally and nor is the market in the shares of Australia's third force in the commodity, Andrew Forrest's Fortescue. It reeks of something very fishy and authorities will need to be taking a very close look at trading in both.

Shares should trade up after good news – not before it. And commodities, like iron ore need a reason to skyrocket 20 per cent.

Monday's Fortescue trading looked a little unusual for most of the day when its shares were up a massive 13 per cent. But in the last half an hour of trading Fortescue shares shot up out of nowhere to end the session up a massive 24 per cent which looks simply implausible.

The forces that drove Fortescue up 13 per cent can be reasonably explained by the previous overnight 5 per cent increase in the iron ore price. The share prices of both BHP and Rio also got a shot of adrenalin – up 5 per cent and 3.5 per cent respectively.