Single Monthly Mortality - SMM

AAA

DEFINITION of 'Single Monthly Mortality - SMM'

In mortgage-backed securities (MBSs), this is the percentage of the principal amount of mortgages that are prepaid in a given month. For investors of MBSs, prepayment of mortgages is usually undesirable since future interest is foregone.


This is more broadly referred to as "prepayment risk." Due to the importance of prepayment risk, single monthly mortality was developed as a metric for tracking prepayments in the mortgage pool.

BREAKING DOWN 'Single Monthly Mortality - SMM'

Prepayment hinders the returns for MBS investors because mortgages are normally prepaid using refinancing loan, and this happens primarily when interest rates have fallen. So while an investor in an MBS believes they have locked in a higher yielding investment in a low rate environment, they may in fact have the carpet pulled out from under them.


The mortgage holders in the MBS may refinance at lower interest rates, and then pay off the mortgage in the MBS pool. Now the investor has their money back and must reinvest the funds in a lower interest rate environment.

RELATED TERMS
  1. Mortgage Putback

    The forced repurchase of a mortgage by an originator from the ...
  2. Prepayment

    The satisfaction of a debt or installment payment before its ...
  3. Prepayment Risk

    The risk associated with the early unscheduled return of principal ...
  4. Prepayment Model

    A model used to estimate the level of prepayments on a loan portfolio ...
  5. Refinancing Risk

    1. The risk that an early unscheduled repayment of principal ...
  6. Mortgage-Backed Security (MBS)

    A type of asset-backed security that is secured by a mortgage ...
Related Articles
  1. Insurance

    Fannie Mae and Freddie Mac, Boon Or Boom?

    These two companies are crucial to the mortgage market, but are they ticking timebombs?
  2. Bonds & Fixed Income

    Profit From Mortgage Debt With MBS

    Mortgage-backed securities can offer monthly income, a fixed interest rate and even government backing.
  3. Insurance

    Behind The Scenes Of Your Mortgage

    Four major players slice and dice your mortgage in the secondary market.
  4. Bonds & Fixed Income

    The Risks Of Mortgage-Backed Securities

    Find out how weighted average life guards against prepayment risk.
  5. Personal Finance

    Why Are Mortgage Rates Increasing?

    Learn how the secondary mortgage market and investor demand affect the cost of home ownership.
  6. Personal Finance

    The Fuel That Fed The Subprime Meltdown

    Take a look at the factors that caused this market to flare up and burn out.
  7. Mutual Funds & ETFs

    ETF Analysis: Guggenheim Enhanced Short Dur

    Find out about the Guggenheim Enhanced Short Duration ETF, and learn detailed information about this fund that focuses on fixed-income securities.
  8. Mutual Funds & ETFs

    ETF Analysis: iShares Core Growth Allocation

    Find out about the iShares Core Growth Allocation Fund, and learn detailed information about its characteristics, suitability and recommendations.
  9. Mutual Funds & ETFs

    ETF Analysis: SPDR Barclays Short Term Hi Yld Bd

    Find out about the SPDR Barclays Short Term High Yield Bond ETF, and explore detailed analysis of the fund that tracks short-term, high-yield corporate bonds.
  10. Mutual Funds & ETFs

    ETF Analysis: SPDR Barclays Short Term Corp Bd

    Learn about the SPDR Barclays Short-Term Corporate Bond ETF, and explore detailed analysis of the exchange-traded fund tracking U.S. short-term corporate bonds.
RELATED FAQS
  1. Where do penny stocks trade?

    Generally, penny stocks are traded through the use of the Over the Counter Bulletin Board (OTCBB) and through pink sheets. ... Read Full Answer >>
  2. Where can I buy penny stocks?

    Some penny stocks, those using the definition of trading for less than $5 per share, are traded on regular exchanges such ... Read Full Answer >>
  3. What are the maximum Social Security disability benefits?

    The maximum Social Security disability benefits for a single eligible person in 2015 are $2,663.  What Are Social Security ... Read Full Answer >>
  4. What is the relationship between the current yield and risk?

    The general relationship between current yield and risk is that they increase in correlation to one another. A higher current ... Read Full Answer >>
  5. How are American Depository Receipts (ADRs) priced?

    The price of an American depositary receipt (ADR) is determined by the bank or other financial institution that issues it. ... Read Full Answer >>
  6. What is a 'busted' convertible bond?

    In finance, a convertible bond represents a hybrid security that offers debt and equity features and risks. While a convertible ... Read Full Answer >>

You May Also Like

Hot Definitions
  1. Alligator Spread

    An unprofitable spread that occurs as a result of large commissions charged on the transaction, regardless of favorable market ...
  2. Tiger Cub Economies

    The four Southeast Asian economies of Indonesia, Malaysia, the Philippines and Thailand. Tiger cub economy indicates that ...
  3. Gorilla

    A company that dominates an industry without having a complete monopoly. A gorilla firm has large control of the pricing ...
  4. Elephants

    Slang for large institutions that have the funds to make high volumes trades. Due to the large volumes of stock that elephants ...
  5. Widow's Exemption

    In general terms, a widow's exemption refers to the amount that can be deducted from taxable income by a widow, thereby reducing ...
  6. Wedding Warrant

    A warrant that can only be exercised if the host asset, typically a bond or preferred stock, is surrendered. Until the call ...
Trading Center
×

You are using adblocking software

Want access to all of Investopedia? Add us to your “whitelist”
so you'll never miss a feature!