A graduated annuity is like a regular annuity, except instead of getting the same cash flow each period, the cash flow grows at a given rate throughout the term. There a two basic types of graduated annuities, ordinary annuities (cash flow comes at the end of each period), and annuities due (cash flow starts at the beginning of each […]

# Category: Rate

## Mortgage Pool – Holding Period Return

This spreadsheet was originally compiled to help make the decision to either sell mortgages that were originated, or keep them. It can also be used to help with the decision to purchase a pool of whole loans, or a securitized mortgage pools. Two different concepts of return are referred to in this post. The two are […]

## Prepayment Penalty

Once upon a time (all my numbers and loans are fictitious) the loan department was negotiating the sale of a parking lot. It seemed that the buyer and we were at a stalemate. We wanted $5,700,000 for the lot and the buyer was only willing to pay $5,500,000. The market rate for this type of loan was […]

## Skip-a-Payment

Around this time of year, banks and credit unions will sometimes offer borrowers the option to skip a payment or two in return for a fee. This offering is a spreadsheet that calculates the APR on a loan after the borrower accepts the offer to skip one or more payments. There are two amortization schedules […]

## Simple Formula for Converting Compound Interest Rates

This workbook has a simple formula to convert compound interest rates. =IF(t>500,f*LN(1+g/f),IF(f>=500,t*(EXP(g/t)-1),(t*((1+g/f)^(f/t))-t))) Where: g = Current interest rate f = Number of times the current rate compounds per year t = Number of times the converted new rate compounds per year This lookup table grabs two of the numbers for the formula Continuous compounding in Excel […]

## Constant Default Rate (CDR)

Also see this post: Comparing CDR Default Formulas to Industry Standard Default Formulas Constant Default Rate (CDR) is an annualized rate of default on a pool of loans. The default rate on loans depends on a number of conditions, such as the age of the loans, seasonality, burnout levels, FICO, LTV, income, etc. Since […]

## Solve for Last Payment Due

In my first blog post back in August, I had a formula that would solve for future value given dates and amounts. In this post we will use the same formula to solve for the last payment due. There are a number of scenarios where the last payment might be needed. Assume for a moment that you won a court judgment […]

## Amortization Schedule With Variable Rates

Note: I have updated this post with more options. See Variable Rate Amortization – Day/Year Count & Last Payment Options. Have you ever wanted an amortization schedule where you can set the rate for one term and then change the rate for another term, and change the rate and term a total of six times? […]

## Mortgage Backed Securities (MBS) “MegaFormula”

See updated formula at: MBS Math Formula. Servicing, CPR, Payment Delay, Default Rate & Loss Severity http://pistulka.com/Other/?p=2384 This post is just to show you 20-somethings what we had to go through to calculate the price of a mortgage backed security back in the day. I had the first desktop computer (before Apple and Radio Shack were […]

## PSA vs. CPR

In past posts I showed you how to calculate a Constant Prepayment Rate (CPR) with an amortization schedule. This post will allow you to compare a CPR rate to a model provided by the Public Securities Association (PSA). PSA is based upon the CPR calculation. Both use a Single Monthly Mortality (SMM) calculation. The difference is […]

## Bonus Checking

To understand this next spreadsheet, you have to take your accounting hat off and put your financing hat on. Consider all your sources of funding; savings accounts, money market accounts, CDs, borrowing, and checking accounts. There may be more, but considering the above, checking accounts will always be the cheapest source of funds. The reason […]

## APR – Fixed Rate Mortgage

Given the inputs in yellow cells, check boxes and option buttons, this sheet uses an amortization schedule to calculate APR (or APY) for a fixed rate mortgage. Both Loan Balance and Interest Rate need no explanations. Truth in Lending Fees are additional dollar costs to the borrower to acquire the loan. Points represent a percent of […]

## PV and FV of Periodic Cash Flows

I thought I had already posted this spreadsheet, but it looks like I missed it. The sheet uses both formulas and Excel functions to calculate the present value, future value and also shows how to calculate the APR and APY on a cash flow, give either the present or future value. This sheet is very […]

## Annuity

There is nothing special about this annuity calculator except: All input is with sliders Each line of the results are one cell text and formulas The dollar growth and payout balances are charted You can pick from monthly deposits or lump sum deposit Inputs: Outputs: Download workbook “Annuity” from: http://www.pistulka.com/Excel_Shared/ Downloads Written in Excel […]

## Simple Mortgage Refi Break-Even

If you do a search, you will find dozens of mortgage refinance calculators on the internet, most on sites of companies that want to sell you a new loan. The big problem with calculating break-even (when the new lower interest rate, will cover the cost to refinance) is: What happens to the difference in monthly payments Where did the money used to […]