Calculating the Modified Internal Rate of Return (MIRR) on a BA II Plus calculator requires understanding the distinct steps that separate it from the traditional Internal Rate of Return. This guide provides a detailed walkthrough of the process, ensuring you can accurately assess the profitability of potential investments. The MIRR addresses a key flaw in the standard IRR by assuming that positive cash flows are reinvested at the firm's cost of capital, rather than at the IRR itself, which is often unrealistic.
Before diving into the specific keystrokes, it is essential to configure your BA II Plus calculator correctly. The calculation relies heavily on the Time Value of Money (TVM) registers, so clearing them first is a critical safety step. You must also ensure your calculator is set to the appropriate calculation mode, either Begin or End, depending on when cash flows occur within each period. For most corporate finance scenarios, the default End mode is appropriate, but verifying this setting prevents significant errors down the line.
Understanding the MIRR Calculation Methodology
The core logic behind the MIRR involves two main phases: compounding and discounting. First, all positive cash flows are compounded forward to the terminal value using the finance rate. Second, the absolute value of the initial investment is discounted back to the present using the finance rate to find the present value of outflows. Finally, the MIRR is the rate that equates the present value of outflows to the future value of inflows over the project's life. Mastering this sequence is the key to mastering the BA II Plus procedure.
Step-by-Step Keystroke Instructions
To calculate MIRR on your BA II Plus, follow this specific sequence of operations. Begin by clearing the TVM registers by pressing [2nd] followed by [FV]. You will see "CLR TVM" flash at the top of the screen; press [ENTER] to confirm. This ensures no residual data interferes with your calculation, which is a common source of mistakes for users.
Next, input the number of periods using the [N] key. After entering the integer value, press [ENTER] to store it. Then, input the finance rate, which is the interest rate used for reinvestment and discounting, and press [ENTER] followed by [I/Y]. This rate is typically the firm's Weighted Average Cost of Capital (WACC). If your cash flows occur at the beginning of periods, you must press [2nd] [BGN] to switch to BGN mode before entering the number of periods.
Compounding the Inflows
After setting the initial variables, you must calculate the future value of the positive cash flows. Start by setting the Net Present Value (NPV) to zero by pressing [2nd] [NPV] if the PV prompt appears. Clear the cash flow registers by pressing [2nd] [CF]. Input the initial investment as a negative number using the [CHS] key, press [ENTER], and then hit [CF0]. Move down using the down arrow to access CO1, input the first cash flow, and repeat this process for all subsequent positive cash flows. Once all cash flows are entered, press [NPV] to display the NPV calculation. To find the future value, manually compound each cash flow to the terminal year using the formula FV = CF * (1 + I/Y)^n, or calculate the net future value by compounding the NPV. Input this final future value into the FV field by pressing [CPT] [FV].
