Firstly, it decreases the income of exporting companies or companies selling their product in US$. Thus, miners suffer.
Steel companies that export suffer but since they buy their inputs in US$ they get cheaper inputs.
Secondly, companies that compete with imports suffer because imports are cheaper relative to home made. See car industry.
However, a higher dollar is the effect of people buying Australian dollars. When those dollars get here they are placed in asset clases like term deposits, bonds or shares. This increases the demand for shares so the market goes up.
It seems that nothing will bring the XJO (ASX200) back up. The US is at a post 2008 high. Where are we? About 1600 points away. A high dollar will help raise it in the short term but longer term will be a negative.
