IDEAS home Printed from
   My bibliography  Save this paper

Interest-Only/Principal-Only Mortgage-Backed Strips: A Valuation and Risk Analysis


  • Alan J. Marcus
  • Arnold Kling


We examine the risk characteristics of each portion of IO/PO mortgage strips, present results of a valuation model of these securities, and examine market prices of both the interest-only and principal-only portions of mortgage pools. We show that IO/PO securities are highly sensitive to the prepayment behavior of the underlying mortgage pool. Because that behavior varies systematically with the interest rate, and because prepayments affect the values of I0 and PO components in opposite ways, the interest-rate risk of strip securities can differ substantially from that of the underlying mortgage pool. The PO component has much longer duration than the underlying mortgage pool. In contrast, the IO component typically will have a negative duration, at least in ranges for which interest-rate movements induce meaningful changes in mortgage prepayment behavior. We also show how market prices of partially-stripped MBSs that are actively traded on secondary markets can be used to infer market values of pure IO/PO strips. Recent market data is fully consistent with the theoretical insights offered by our valuation model. When interest rates spiked last April, PO values fell far more dramatically than those of the underlying mortgage pool while IO values actually rose.

Suggested Citation

  • Alan J. Marcus & Arnold Kling, 1987. "Interest-Only/Principal-Only Mortgage-Backed Strips: A Valuation and Risk Analysis," NBER Working Papers 2340, National Bureau of Economic Research, Inc.
  • Handle: RePEc:nbr:nberwo:2340
    Note: ME

    Download full text from publisher

    File URL:
    Download Restriction: no

    References listed on IDEAS

    1. Dunn, Kenneth B & McConnell, John J, 1981. "A Comparison of Alternative Models for Pricing GNMA Mortgage-Backed Securities," Journal of Finance, American Finance Association, vol. 36(2), pages 471-484, May.
    2. Brennan, Michael J. & Schwartz, Eduardo S., 1977. "Savings bonds, retractable bonds and callable bonds," Journal of Financial Economics, Elsevier, vol. 5(1), pages 67-88, August.
    Full references (including those not matched with items on IDEAS)

    More about this item


    Access and download statistics


    All material on this site has been provided by the respective publishers and authors. You can help correct errors and omissions. When requesting a correction, please mention this item's handle: RePEc:nbr:nberwo:2340. See general information about how to correct material in RePEc.

    For technical questions regarding this item, or to correct its authors, title, abstract, bibliographic or download information, contact: () or (Joanne Lustig). General contact details of provider: .

    If you have authored this item and are not yet registered with RePEc, we encourage you to do it here. This allows to link your profile to this item. It also allows you to accept potential citations to this item that we are uncertain about.

    If CitEc recognized a reference but did not link an item in RePEc to it, you can help with this form .

    If you know of missing items citing this one, you can help us creating those links by adding the relevant references in the same way as above, for each refering item. If you are a registered author of this item, you may also want to check the "citations" tab in your RePEc Author Service profile, as there may be some citations waiting for confirmation.

    Please note that corrections may take a couple of weeks to filter through the various RePEc services.

    IDEAS is a RePEc service hosted by the Research Division of the Federal Reserve Bank of St. Louis . RePEc uses bibliographic data supplied by the respective publishers.