
Paper P4: Advanced Financial Management
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3.4 Modified internal rate of return (MIRR)
A criticism of the IRR method is that in calculating the IRR, an assumption is that all
cash flows earned by the project can be reinvested to earn a return equal to the IRR.
For example, suppose that a project has an NPV of + $300,000 when discounted at
the cost of capital of 8%, and the IRR of the project is 14%. In calculating the IRR, an
assumption would be that all cash flows from the project will be reinvested as soon
as they are received to earn a return of 14% - even though the company’s cost of
capital is only 8%.
Modified internal rate of return is a calculation of the return from a project, as a
percentage yield, where it is assumed that cash flows earned from a project will be
reinvested to earn a return equal to the company’s cost of capital. So in the previous
example of the project with an NPV of $300,000 at a cost of capital of 8%, MIRR
would be calculated using the assumption that project cash flows are reinvested
when they are received to earn a return of 8% per year.
Using MIRR for project appraisal
It might be argued that if a company wishes to use the discounted return on
investment as a method of capital investment appraisal, it should use MIRR rather
than IRR, because MIRR is more realistic because it is based on the cost of capital as
the reinvestment rate.
Calculating MIRR
The MIRR of a project is calculated as follows:
Step 1. Take the negative net cash flows in the early years of the project, and
discount these to a present value. The total PV of these cash flows is the PV of
the investment phase of the project. If the only year of negative cash flow is Year
0, the PV of the investment phase is the cash flow in Year 0. However, if there
are negative cash flows in Year 1, or Year 1 and 2, discount these to a present
value and add them to the Year 0 cash outflow.
Step 2. Take the cash flows from the year that the project cash flows start to turn
positive and compound these to an end-of-project terminal value, assuming that
cash flows are reinvested at the cost of capital. For example, if cash flows are
positive from Year 1 of a five-year project:
-
compound the cash flow in Year 1 to and end-of-year 5 value using the
cost of capital as the compound rate
-
compound the cash flow in Year 2 to and end-of-year 5 value using the
cost of capital as the compound rate
-
compound the cash flow in Year 3 to and end-of-year 5 value using the
cost of capital as the compound rate
-
compound the cash flow in Year 4 to and end-of-year 5 value using the
cost of capital as the compound rate
-
add the compounded values for each year to the cash flow at the end of
Year 5.