Principles of Managerial Finance

average cost of capital.Therefore, it is useful to calculate theweighted marginal

cost of capital (WMCC),which is simply the firm’s weighted average cost of cap-

ital (WACC) associated with itsnext dollarof total new financing. This marginal

cost is relevant to current decisions.

The costs of the financing components (debt, preferred stock, and common

stock) rise as larger amounts are raised. Suppliers of funds require greater returns

in the form of interest, dividends, or growth as compensation for the increased

risk introduced by larger volumes ofnewfinancing. The WMCC is therefore an

increasing function of the level of total new financing.

Another factor that causes the weighted average cost of capital to increase is

the use of common stock equity financing. New financing provided by common

stock equity will be taken from available retained earnings until this supply is

exhausted and then will be obtained through new common stock financing.

Because retained earnings are a less expensive form of common stock equity

financing than the sale of new common stock, the weighted average cost of capi-

tal will rise with the addition of new common stock.

Finding Break Points

To calculate the WMCC, we must calculate break points,which reflect the level

of totalnew financing at which the cost of one of the financing components rises.

The following general equation can be used to find break points:

BPj (11.10)

where

BPjbreak point for financing source j

AFjamount of funds available from financing source jat a given cost

wjcapital structure weight (stated in decimal form) for financing source j

EXAMPLE When Duchess Corporation exhausts its $300,000 of available retained earnings

(at kr13.0%), it must use the more expensive new common stock financing (at

kn14.0%) to meet its common stock equity needs. In addition, the firm expects

that it can borrow only $400,000 of debt at the 5.6% cost; additional debt will

have an after-tax cost (ki) of 8.4%. Two break points therefore exist: (1) when

the $300,000 of retained earnings costing 13.0% is exhausted, and (2) when the

$400,000 of long-term debt costing 5.6% is exhausted.

The break points can be found by substituting these values and the corre-

sponding capital structure weights given earlier into Equation 11.10. We get the

dollar amounts of totalnew financing at which the costs of the given financing

sources rise:

BPcommon equity$600,000

BPlong-term debt$1,000,000

$400,000



0.40

$300,000



0.50

AFj



wj

CHAPTER 11 The Cost of Capital 485

break point
The level of totalnew financing
at which the cost of one of the
financing components rises,
thereby causing an upward shift
in the weighted marginal cost of
capital (WMCC).

weighted marginal cost
of capital (WMCC)
The firm’s weighted average cost
of capital (WACC) associated
with its next dollarof total new
financing.