## Calculating Historical CPR

There is a newer post that replaces the amortization schedule to calculate historic PSA with a UDF: http://pistulka.com/Other/?p=2964   Back in December of 2014 I wrote a post and Excel spreadsheet called Reverse Engineering Constant Prepayment Rate (CPR). I called it that because instead of giving a CPR to a model, we could do the reverse and calculate the […]

## Certificate of Deposit Ladder Optimizer

There are all kinds of calculators you can find to “optimize” your rate of return by laddering certificates. Of course the term optimize is a misnomer because you don’t know what the reinvestment rate will be on the shorter term CDs.  There are some advantages to laddering such as, if you need the funds earlier than expected, you can […]

## Conforming the “Mega” MBS Formula to Street Conventions

See updated formula at: MBS Math Formula. Servicing, CPR, Payment Delay, Default Rate & Loss Severity http://pistulka.com/Other/?p=2384 This adjustment to the mega formula for mortgage-backed securities only affects those that use an odd first payment, by entering an amount other than 30, in the “Payment Days Delay” cell. It was pointed out by Win Smith (The Well-Tempered Spreadsheet) […]

## Chained Returns

Calculating the total rate of return on a chain of returns produces a time weighted rate of return. I covered this in my post “Time & Dollar Weighted Rates of Return Calculator“. In this spreadsheet I have segregate the time weighted return into an easier calculator for someone interested in taking their annual, monthly, quarterly, etc. […]

## Rule of 78

If you normally sell your car before it is paid off, you are going to want to stay away from lenders that still use the Rule of 78 (also known as sum-of-the-digits) to calculate the interest you have accrued. This method was used before the technology was available to calculate a prepayment on the spot. At a […]