
Paper F9: Financial management
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Cost of capital and gearing
The traditional view of gearing and WACC
The Modigliani-Miller view: ignoring corporate taxation
The Modigliani-Miller view: allowing for corporate taxation
5 Cost of capital and gearing
For a given level of annual cash profits before interest and tax, the value of a
company (equity + debt) is maximised at the level of gearing where WACC is
lowest. This should also be the level of gearing that optimises the wealth of the
company’s equity shareholders.
The question is therefore: Is there a level of gearing where the WACC is minimised?
If WACC is minimised at a particular level of gearing a company should try to
achieve a capital structure where this minimum WACC occurs.
However, there are different theories about the relationship between WACC and
gearing. The three you need to know are:
The traditional theory of WACC and gearing
Modigliani and Miller’s theory of WACC, ignoring taxation
Modigliani and Miller’s theory of WACC, allowing for taxation.
5.1 The traditional view of gearing and WACC
The traditional view of gearing is that there is an optimum level of gearing for a
company, where WACC is minimised. This theory is based on the following
assumptions.
As gearing increases, the cost of equity rises. However, as gearing increases,
there is also a greater proportion of debt capital in the capital structure, and the
cost of debt is cheaper than the cost of equity.
As gearing increases, WACC is therefore affected by a higher cost of equity, but
a larger proportion of cheaper debt capital.
At lower levels of gearing, as gearing increases, the effect of having more debt
capital has a bigger effect on the WACC than the rising cost of equity.
Consequently the WACC falls as gearing increases.
However, after a certain level of gearing is reached, if gearing continues to
increase, the increase in the cost of equity has a greater effect on WACC than the
larger proportion of cheap debt capital. The WACC starts to rise.
The traditional view of gearing is therefore that an optimum level of gearing exists,
where WACC is minimised and the value of the company is maximised. A graph of
WACC at different levels of gearing can be drawn as a saucer-shaped or bowl-
shaped curve.