Skip to Main Content Skip to Search
Product Documentation

mbsoas2yield - Yield given option-adjusted spread

Syntax

[MYield, BEMBSYield] = mbsoas2yield(ZeroCurve, OAS, Settle, 
Maturity, IssueDate, GrossRate, CouponRate, Delay, Interpolation, 
PrepaySpeed, PrepayMatrix)

Arguments

ZeroCurve

A matrix of three columns:

  • Column 1: Serial date numbers.

  • Column 2: Spot rates with maturities corresponding to the dates in Column 1, in decimal (for example, 0.075).

  • Column 3: Compounding of the rates in Column 2. (This is the agency spot rate on the settlement date.)

OAS

Option-adjusted spreads in basis points.

Settle

Settlement date (scalar only). A serial date number or date string. Date when option-adjusted spread is calculated. Settle must be earlier than Maturity.

Maturity

Maturity date. Scalar or vector in serial date number or date string format.

IssueDate

Issue date. A serial date number or date string.

GrossRate

Gross coupon rate (including fees), in decimal.

CouponRate

(Optional) Net coupon rate, in decimal. Default = GrossRate.

Delay

(Optional) Delay (in days) between payment from homeowner and receipt by bondholder. Default = 0 (no delay between payment and receipt).

Interpolation

Interpolation method. Computes the corresponding spot rates for the bond's cash flow. Available methods are (0) nearest, (1) linear, and (2) cubic spline. Default = 1. See interp1 for more information.

PrepaySpeed

(Optional) Relation of the conditional payment rate (CPR) to the benchmark model. Default = end of month's CPR. Set PrepaySpeed to [] if you input a customized prepayment matrix.

PrepayMatrix

(Optional) Customized prepayment matrix. A matrix of size max(TermRemaining)-by-NMBS. Missing values are padded with NaNs. Each column corresponds to a mortgage-backed security, and each row corresponds to each month after settlement.

All inputs (except PrepayMatrix) are number of mortgage-backed securities (NMBS) by 1 vectors.

Description

[MYield, BEMBSYield] = mbsoas2yield(ZeroCurve, OAS, Settle, Maturity, IssueDate, GrossRate, CouponRate, Delay, Interpolation, PrepaySpeed, PrepayMatrix) computes the mortgage and bond-equivalent yields of a pass-through security.

MYield is the yield to maturity of the mortgage-backed security (the mortgage yield). This yield is compounded monthly (12 times per year). For example:

0.075 (7.5%)

BEMBSYield is the corresponding bond equivalent yield of the mortgage-backed security. This yield is compounded semiannually (two times per year). For example:

0.0761 (7.61%)

Examples

Given an option-adjusted spread, a spot curve, and a prepayment assumption, compute the theoretical yield to maturity of a mortgage pool.

Create the bonds matrix.

Bonds = [datenum('11/21/2002')   0       100  0  2  1;
         datenum('02/20/2003')   0       100  0  2  1;
         datenum('07/31/2004')   0.03    100  2  3  1;
         datenum('08/15/2007')   0.035   100  2  3  1;
         datenum('08/15/2012')   0.04875 100  2  3  1;
         datenum('02/15/2031')   0.05375 100  2  3  1];

Choose a settlement date.

Settle = datenum('08/20/2002');

Assume these clean prices for the bonds.

Prices =  [ 98.97467;
            98.58044;
           100.10534;
            98.18054;
           101.38136;
            99.25411];

Use this formula to compute spot compounding for the bonds.

SpotCompounding = 2*ones(size(Prices));

Compute the zero curve.

[ZeroRatesP, CurveDatesP] = zbtprice(Bonds, Prices, Settle);
ZeroCurve = [CurveDatesP, ZeroRatesP, SpotCompounding];

Assign parameters.

OAS           = [26.0502; 28.6348; 31.2222];
Maturity      = datenum('02-Jan-2030');
IssueDate     = datenum('02-Jan-2000');
GrossRate     = 0.08125;
CouponRate    = 0.075;
Delay         = 14;
Interpolation = 1;
PrepaySpeed   = [0 50 100];

Compute the mortgage yield and bond equivalent mortgage yield.

[MYield BEMBSYield] = mbsoas2yield(ZeroCurve, OAS, Settle, ...
Maturity, IssueDate, GrossRate, CouponRate, Delay, ... 
Interpolation, PrepaySpeed)

MYield =

    0.0802
    0.0814
    0.0828

BEMBSYield =

    0.0816
    0.0828
    0.0842

See Also

mbsoas2price | mbsprice2oas | mbsyield2oas

  


Free Interactive Computational Finance CD

View demos and recorded presentations led by industry experts.

Now On Demand
Network with industry peers and learn the latest applications of the leading software product for computational finance.

 © 1984-2012- The MathWorks, Inc.    -   Site Help   -   Patents   -   Trademarks   -   Privacy Policy   -   Preventing Piracy   -   RSS