Adjustable-Rate Mortgage

An adjustable-rate mortgage (ARM) is a home loan where the interest rate is fixed for an initial period (typically 3–10 years), then adjusts periodically (usually annually) based on market conditions. While ARMs typically offer a lower initial rate, they carry the risk of significantly higher payments when the rate adjusts.

How ARMs work

An ARM is typically labeled “5/1” or “7/1,” meaning:

• 5 = rate is fixed for 5 years
• 1 = rate adjusts annually thereafter

Example: you borrow $240,000 on a 5/1 ARM at 4.5%. For five years, your payment is $1,216 (principal + interest at 4.5%). In year 6, the rate adjusts. If the new rate is 6%, your payment jumps to $1,439. If it rises to 7%, your payment is $1,596.

Why ARMs exist

Lenders offer lower initial rates on ARMs to attract borrowers. This made sense historically when mortgage rates were 7–9%; an ARM at 5% was attractive. Today, when fixed rates are 6–7%, ARM rates might be 5–5.5%, which is a modest savings.

For borrowers, ARMs make sense only if you plan to sell or refinance before the rate adjusts (i.e., within the initial fixed period).

The danger

If rates rise sharply and you still own the home:

• Your payment increases, potentially by hundreds of dollars per month.
• You cannot afford the new payment and default.
• You refinance into a higher-rate loan (rates have risen).
• You are stuck paying a high rate you did not anticipate.

The 2008 financial crisis was partly caused by ARMs: borrowers took 2/28 and 3/27 ARMs (adjustable after 2–3 years) with low teaser rates, expecting to refinance before rates adjusted. When housing prices fell and rates rose, refinancing became impossible and foreclosures surged.

Rate caps

ARMs have caps limiting how much the rate can increase:

• Periodic cap. Maximum increase per adjustment (e.g., 2% per year).
• Lifetime cap. Maximum increase over the life of the loan (e.g., 6% total).

Example: a 4.5% ARM with a 2% periodic cap and 6% lifetime cap can reach maximum 6% (initial 4.5% + 6% lifetime cap), not 10.5%.

Caps provide some protection but do not eliminate the risk if you cannot afford the higher payments.

When ARMs might make sense

1. You will definitely move. You plan to sell in 4 years; a 5/1 ARM is fine.
2. You will definitely refinance. You expect to refinance in 5 years before rates adjust.
3. Interest rates are very high. If fixed rates are 8% and ARM rates are 5%, the savings are substantial for the initial period.

For most homeowners, these conditions are not met. Fixed-rate mortgages are simpler and safer.

Refinancing risk

If you plan to refinance before the rate adjusts, you depend on:

1. Home value staying flat or rising. If it falls, you cannot refinance (owe more than the home is worth).
2. Your credit score staying good. If your score drops, refinancing is expensive or impossible.
3. Interest rates cooperating. If rates have risen by the time you refinance, you may not improve your situation.

The 2008 crisis showed that refinancing is not guaranteed. Many borrowers could not refinance when ARMs adjusted because home values had fallen and rates had risen.

ARM vs. fixed-rate today

Current environment (2024):

• 30-year fixed rate: ~6–7%
• 5/1 ARM rate: ~5–5.5%

Savings: $150–$250 per month for 5 years = ~$9,000–$15,000 total.

To justify an ARM, you must be confident you will sell or refinance and save enough to offset the risk. For most people, the fixed-rate peace of mind is worth 0.5–1%.

See also