Mortgage-Backed Security (MBS)

What Does Mortgage-Backed Security (MBS) Mean?
A type of asset-backed security that is secured by a mortgage or collection of mortgages. These securities must also be grouped in one of the top two ratings as determined by a accredited credit rating agency, and usually pay periodic payments that are similar to coupon payments. Furthermore, the mortgage must have originated from a regulated and authorized financial institution.

Also known as a "mortgage-related security" or a "mortgage pass through".

Investopedia explains Mortgage-Backed Security (MBS)
When you invest in a mortgage-backed security you are essentially lending money to a home buyer or business. An MBS is a way for a smaller regional bank to lend mortgages to its customers without having to worry about whether the customers have the assets to cover the loan. Instead, the bank acts as a middleman between the home buyer and the investment markets.

This type of security is also commonly used to redirect the interest and principal payments from the pool of mortgages to shareholders. These payments can be further broken down into different classes of securities, depending on the riskiness of different mortgages as they are classified under the MBS.