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The PSA Prepayment Model is a prepayment scale developed by the Public Securities Association for analyzing American mortgage-backed securities. The PSA model assumes increasing prepayment rates for the first 30 months after mortgage origination and a constant prepayment rate thereafter. Real-world experience shows that during the first few years, mortgage borrowers: # are less likely to relocate to a different home, # are less likely to refinance into a new mortgage, and # are less likely to make extra payments of principal. The standard model (also called "100% PSA") works as follows: Starting with an annualized full prepayment rate of 0.2% in month 1, the rate increases by 0.2% each month, until it reaches 6% in month 30. From the 30th month onward, the model assumes an annualized prepayment rate of 6% of the remaining balance.〔Hayre, Lakhbir, ''Salomon Smith Barney Guide to Mortgage-Backed and Asset-Backed Securities'' (Wiley: 2001) ISBN 978-0-471-38587-5, p.24〕 Variations of the model are expressed in percent; e.g., "150% PSA" means a monthly increase of 0.3% in the annualized prepayment rate, until the peak of 9% is reached after 30 months. The months thereafter have a constant annualized prepayment rate of 9%. 1667% PSA is roughly equivalent to 100% prepayment rate in month 30 or later. == References == 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「PSA prepayment model」の詳細全文を読む スポンサード リンク
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