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Personal Financial Planning — Part 2: Managing Basic Assets · 11 of 12
Personal Financial Planning — Part 2: Managing Basic Assets
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Mortgage Types & Risk Transfer

Personal Financial Planning — Part 2: Managing Basic Assets Gitman, Joehnk, and Billingsley
mortgage ARM fixed-rate refinancing negative-amortization FHA VA prepayment biweekly

Key Principle

Every mortgage product is a bet on who bears interest-rate risk. Fixed-rate mortgages price that risk into a higher rate paid by the borrower in exchange for certainty; ARMs shift rate risk to the borrower in exchange for a lower starting rate. Choosing the right structure means matching your time horizon and volatility tolerance to the risk allocation embedded in the product.

Why This Matters

The initial rate on a mortgage is not the cost of the mortgage — the risk structure is. A borrower who takes an ARM for the low teaser rate without understanding adjustment mechanics, negative amortization, or their own holding period is accepting risk they have not priced. Conversely, a buyer who locks a 30-year fixed when they plan to move in three years overpays for stability they will never use. Every mortgage decision is a risk-transfer decision first and a rate decision second.

Good Examples

15-year vs. 30-year interest savings (p. 175):

  • $160,000 at 5%: 30-year payment = $858.91/mo, total interest = $149,209. 15-year payment = $1,265.27/mo, total interest = $67,749.
  • The 15-year saves ~$81,460 for only ~$406/month more — the payment is roughly 20% larger, not double.
  • 15-year rates typically run ~0.5 percentage points below comparable 30-year rates.

Negative amortization trap (p. 177):

  • $100,000 ARM at 5.5%, payment = $568/mo. Rate rises to 7%, requiring $663. Payment cap holds payment at $568. The $95/mo shortfall adds to principal — balance grows to $100,950 after 10 months.
  • A borrower-protection feature (payment cap) paradoxically erodes equity.

Refinancing break-even — D'Angelo family (p. 180):

  • Old: $80,000 at 8%, 30-year (balance $70,180, payment $587/mo).
  • New: $70,180 at 5%, 20-year (payment $463/mo).
  • After-tax savings at 25% bracket: $93/mo. Costs: $2,400. Break-even: 26 months.
  • Plan to stay 60+ months — refinancing clearly justified.

Prepayment power (p. 181):

  • Adding just $25/month extra on a 30-year, 6%, $100,000 mortgage cuts the term to ~26 years and saves ~$18,500 in interest.

Counterpoints

  • The "take the 30-year and invest the difference" strategy is theoretically valid but requires both discipline and consistently earning above the mortgage rate. "Because both of these conditions are unlikely, you're best off taking the mortgage that most closely meets your financial needs." (p. 175)
  • ARM teaser rates may be artificially low and disconnected from the index. Always verify the first-year rate against the actual index plus margin. (p. 177)
  • Refinancing at a lower rate can still increase total interest if the borrower extends the term back to 30 years on a partially-paid loan. (p. 181)
  • The tax-deduction argument against refinancing is misleading: "Although the interest deduction may indeed be reduced because of refinancing, the more important concern is the amount of the actual after-tax cash payments." (p. 181)

Key Quotes

  • "Be wary of lenders with very low rates. Ask them if the first-year rate is based on the index and verify the rate yourself." (p. 177)
  • "Paying only an additional $25 per month on a 30-year, 6%, $100,000 mortgage reduces the term to about 26 years and saves about $18,500 in interest." (p. 181)
  • "Although the interest deduction may indeed be reduced because of refinancing, the more important concern is the amount of the actual after-tax cash payments." (p. 181)
  • "Because both of these conditions are unlikely, you're best off taking the mortgage that most closely meets your financial needs." (p. 175)

Rules of Thumb

  1. Risk-allocation pricing: Fixed-rate = lender bears rate risk (highest rate). ARM = borrower bears rate risk (initial rate 2-3 points lower). Match the product to your holding period. (p. 175-176)
  2. ARM five-component check: Before accepting any ARM, verify the adjustment period, index rate, margin, interest rate caps (periodic 1-2 pts, lifetime 5-8 pts), and payment caps. (p. 176)
  3. Negative amortization screen: Reject any ARM with payment caps but no interest rate caps — or understand that payment caps can cause your balance to grow even while you make every payment. (p. 177)
  4. Convertible ARM window: Conversion to fixed is typically available months 13-60 at ~$500 fee, with the fixed rate set 0.25-0.5% above market. (p. 177)
  5. Refinancing trigger: Consider refinancing when rates drop 1-2%+ below your current rate. Run the break-even: total refi costs / after-tax monthly savings = months to recoup. Proceed only if break-even is well under your remaining stay. (pp. 180-181)
  6. Never extend the term: When refinancing, match or shorten the original payoff date. A new 30-year loan on an existing balance resets amortization and can increase total interest even at a lower rate. (p. 181)
  7. Check your own lender first: Existing lenders often refinance with fewer points and lower closing costs than a new lender. (p. 181)
  8. Prepayment beats structured products: A standard fixed-rate mortgage with voluntary prepayment achieves the same acceleration as biweekly or growing-equity mortgages — without rigidity or extra fees. (pp. 178-179)
  9. Government-backed loans: FHA requires minimum 3% down with below-market rates (~0.5-1% lower). VA offers zero down for eligible veterans at ~0.5% below conventional. Both carry insurance/funding fees. (p. 179)
  10. Equity gate for refinancing: Most lenders require at least 20% equity (current appraised value) to refinance. (p. 181)

Related References

  • mortgage-affordability (dual-constraint framework, PITI caps, amortization mechanics)
  • housing-rent-or-buy (rent-vs-buy decision framework)
  • core-framework (asset management principles)