Commonly known as an ARM, is a type of mortgage that has an interest rate that adjusts periodically based on changes in a financial index. The interest rate may go up or down, affecting the borrower's monthly mortgage payments. ARMs are typically offered with a fixed rate for an initial period, after which the rate adjusts regularly.

What is an ARM?

An ARM is a mortgage that has an interest rate that can change over time. The interest rate is typically fixed for a set period, such as five or seven years, and then adjusts periodically based on a predetermined index, such as the prime rate or the London Interbank Offered Rate (LIBOR). The adjustment can result in a higher or lower interest rate, which can affect the monthly mortgage payments.

How does an ARM work? 

An ARM has several key features that distinguish it from a traditional fixed-rate mortgage:

1. Initial Fixed Rate: The interest rate on an ARM is fixed for an initial period, such as five or seven years. The interest rate does not change, and the monthly mortgage payment remains constant.

2. Adjustment Period: After the initial fixed period, the interest rate can adjust periodically, typically once a year. The adjustment is based on a predetermined index and can result in a higher or lower interest rate.

3. Caps: Most ARMs have caps that limit how much the interest rate can increase or decrease in a given period. There are typically two types of caps: a periodic cap, which limits the amount the interest rate can change from one adjustment period to the next, and a lifetime cap, which limits the total amount the interest rate can change over the life of the loan.

Advantages of ARMs for real estate investors 

ARMS can offer several advantages to real estate investors, including:

1. Lower Initial Payments: ARMs often have lower initial payments than traditional fixed-rate mortgages, which can make them more affordable for real estate investors and may be particularly beneficial for investors who plan to sell the property before the initial fixed period ends.

2. Flexibility: ARMs can provide greater flexibility for real estate investors who may need to sell or refinance the property before the end of the initial fixed period. If interest rates are low, investors may be able to take advantage of lower rates to refinance the mortgage and reduce their monthly payments.

Disadvantages of ARMs for real estate investors

ARMS can also have some disadvantages for real estate investors, including:

1. Uncertainty: The uncertainty of not knowing how much the monthly mortgage payment will be after the initial fixed period can be a disadvantage for some investors. If interest rates rise significantly, the monthly payment could increase substantially.

2. Risk: ARMs can be riskier than traditional fixed-rate mortgages, as the interest rate can adjust upward, potentially resulting in a higher monthly payment. This risk is particularly significant if interest rates rise rapidly, which can make it difficult for investors to afford the mortgage payment.

An adjustable-rate mortgage is a type of mortgage in which the interest rate can change over time. 

ARMs can offer lower initial payments and greater flexibility for real estate investors but also come with uncertainties and risks. Investors should carefully consider the pros and cons of an ARM and evaluate their financial situation before deciding whether this type of mortgage is right for them.