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A mortgage-backed security (MBS) is a type of asset-backed security that is secured by a mortgage or collection of mortgages. The mortgages are sold to a group of individuals (a government agency or investment bank) that securitizes, or packages, the loans together into a security that investors can buy. The mortgages of an MBS may be residential or commercial, depending on whether it is an Agency MBS or a Non-Agency MBS; in the United States they may be issued by structures set up by government-sponsored enterprises like Fannie Mae or Freddie Mac, or they can be "private-label", issued by structures set up by investment banks. The structure of the MBS may be known as "pass-through", where the interest and principal payments from the borrower or homebuyer pass through it to the MBS holder, or it may be more complex, made up of a pool of other MBSs. Other types of MBS include collateralized mortgage obligations (CMOs, often structured as real estate mortgage investment conduits) and collateralized debt obligations (CDOs).〔Lemke, Lins and Picard, ''Mortgage-Backed Securities'', Chapters 4 and 5 (Thomson West, 2013 ed.).〕 The shares of subprime MBSs issued by various structures, such as CMOs, are not identical but rather issued as tranches (French for "slices"), each with a different level of priority in the debt repayment stream, giving them different levels of risk and reward. Tranches—especially the lower-priority, higher-interest tranches—of an MBS are/were often further repackaged and resold as collaterized debt obligations.〔(How can mortgage-backed securities bring down the U.S. economy? )| Josh Clark| How Stuff Works〕 These subprime MBSs issued by investment banks were a major issue in the subprime mortgage crisis of 2006–8. The total face value of an MBS decreases over time, because like mortgages, and unlike bonds, and most other fixed-income securities, the principal in an MBS is not paid back as a single payment to the bond holder at maturity but rather is paid along with the interest in each periodic payment (monthly, quarterly, etc.). This decrease in face value is measured by the MBS's "factor", the percentage of the original "face" that remains to be repaid. ==Securitization== The process of securitization is complex and depends greatly on the jurisdiction within which the process is conducted. Among other things, securitization distributes risk and permits investors to choose different levels of investment and risk.〔Lemke, Lins and Picard, ''Mortgage-Backed Securities'', Chapter 1 (Thomson West, 2013 ed.).〕 The basics are: # Mortgage loans (mortgage notes) are purchased from banks and other lenders, and possibly assigned to a special purpose vehicle (SPV). # The purchaser or assignee assembles these loans into collections, or "pools". # The purchaser or assignee securitizes the pools by issuing mortgage-backed securities. While a residential mortgage-backed security (RMBS) is secured by single-family or two- to four-family real estate, a commercial mortgage-backed security (CMBS) is secured by commercial and multi-family properties, such as apartment buildings, retail or office properties, hotels, schools, industrial properties, and other commercial sites. A CMBS is usually structured as a different type of security than an RMBS. These securitization trusts may be structured by government-sponsored enterprises as well as by private entities that may offer credit enhancement features to mitigate the risk of prepayment and default associated with these mortgages. Since residential mortgage holders in the United States have the option to pay more than the required monthly payment (curtailment) or to pay off the loan in its entirety (prepayment), the monthly cash flow of an MBS is not known in advance, and an MBS therefore presents a risk to investors. In the United States, the most common securitization trusts are sponsored by Fannie Mae and Freddie Mac, US government-sponsored enterprises. Ginnie Mae, a US government-sponsored enterprise backed by the full faith and credit of the US government, guarantees that its investors receive timely payments but buys limited numbers of mortgage notes. Some private institutions also securitize mortgages, known as "private-label" mortgage securities.〔(【引用サイトリンク】url=http://www.sec.gov/answers/mortgagesecurities.htm )〕 Issuances of private-label mortgage-backed securities increased dramatically from 2001 to 2007 and then ended abruptly in 2008, when real estate markets began to falter. An example of a private-label issuer is the real estate mortgage investment conduit (REMIC), a tax-structure entity usually used for CMOs; among other things, a REMIC structure avoids so-called double taxation.〔Lemke, Lins and Picard, ''Mortgage-Backed Securities'', Chapter 4 (Thomson West, 2013 ed.).〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Mortgage-backed security」の詳細全文を読む スポンサード リンク
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