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# capbyhw

Price cap instrument from Hull-White interest-rate tree

## Description

example

[Price,PriceTree] = capbyhw(HWTree,Strike,Settle,Maturity) computes the price of a cap instrument from a Hull-White interest-rate tree. capbyhw computes prices of vanilla caps and amortizing caps.

Note

Alternatively, you can use the Cap object to price cap instruments. For more information, see Get Started with Workflows Using Object-Based Framework for Pricing Financial Instruments.

example

[Price,PriceTree] = capbyhw(___,CapReset,Basis,Principal,Options) adds optional arguments.

## Examples

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Load the file deriv.mat, which provides HWTree. The HWTree structure contains the time and interest-rate information needed to price the cap instrument.

load deriv.mat;

Set the required values. Other arguments will use defaults.

Strike = 0.03;
Settle = datetime(2004,1,1);
Maturity = datetime(2007,1,1);

Use capbyhw to compute the price of the cap instrument.

Price = capbyhw(HWTree, Strike, Settle, Maturity)
Price = 2.3090

Define the RateSpec.

Rates = [0.035; 0.042; 0.047; 0.052; 0.054];
ValuationDate = datetime(2014,4,1);
StartDates = ValuationDate;
EndDates = datetime(2019,4,1);
Compounding = 1;
RateSpec = intenvset('ValuationDate', ValuationDate,'StartDates', StartDates,...
'EndDates', EndDates,'Rates', Rates, 'Compounding', Compounding)
RateSpec = struct with fields:
FinObj: 'RateSpec'
Compounding: 1
Disc: [5x1 double]
Rates: [5x1 double]
EndTimes: [5x1 double]
StartTimes: [5x1 double]
EndDates: 737516
StartDates: 735690
ValuationDate: 735690
Basis: 0
EndMonthRule: 1

Define the cap instruments.

Settle = datetime(2014,4,1);
Maturity = datetime(2018,4,1);
Strike = 0.055;
CapReset = 1;
Principal ={{datetime(2015,4,1) 100;datetime(2016,4,1) 60;datetime(2017,4,1) 40;datetime(2018,4,1) 20};
100};

Build the HW Tree.

VolDates = [datetime(2015,4,1) ; datetime(2016,4,1) ; datetime(2017,4,1) ; datetime(2018,4,1)];
VolCurve = 0.05;
AlphaDates = datetime(2018,4,1);
AlphaCurve = 0.10;

HWVolSpec = hwvolspec(RateSpec.ValuationDate, VolDates, VolCurve,...
AlphaDates, AlphaCurve);
HWTimeSpec = hwtimespec(RateSpec.ValuationDate, VolDates, Compounding);
HWTree = hwtree(HWVolSpec, RateSpec, HWTimeSpec)
HWTree = struct with fields:
FinObj: 'HWFwdTree'
VolSpec: [1x1 struct]
TimeSpec: [1x1 struct]
RateSpec: [1x1 struct]
tObs: [0 1 2 3]
dObs: [735690 736055 736421 736786]
CFlowT: {[4x1 double]  [3x1 double]  [2x1 double]  [4]}
Probs: {[3x1 double]  [3x3 double]  [3x5 double]}
Connect: {[2]  [2 3 4]  [2 3 4 5 6]}
FwdTree: {1x4 cell}

Price the amortizing and vanilla caps.

Basis = 0;
Price  = capbyhw(HWTree, Strike, Settle, Maturity, CapReset, Basis, Principal)
Price = 2×1

1.6754
4.6149

## Input Arguments

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Interest-rate tree structure, specified by using hwtree.

Data Types: struct

Rate at which cap is exercised, specified as a NINST-by-1 vector of decimal values.

Data Types: double

Settlement date for the cap, specified as a NINST-by-1 vector using a datetime array, string array, or date character vectors. The Settle date for every cap is set to the ValuationDate of the HW tree. The cap argument Settle is ignored.

To support existing code, capbyhw also accepts serial date numbers as inputs, but they are not recommended.

Maturity date for the cap, specified as a NINST-by-1 vector using a datetime array, string array, or date character vectors.

To support existing code, capbyhw also accepts serial date numbers as inputs, but they are not recommended.

(Optional) Reset frequency payment per year, specified as a NINST-by-1 vector.

Data Types: double

(Optional) Day-count basis representing the basis used when annualizing the input forward rate, specified as a NINST-by-1 vector of integers.

• 0 = actual/actual

• 1 = 30/360 (SIA)

• 2 = actual/360

• 3 = actual/365

• 4 = 30/360 (PSA)

• 5 = 30/360 (ISDA)

• 6 = 30/360 (European)

• 7 = actual/365 (Japanese)

• 8 = actual/actual (ICMA)

• 9 = actual/360 (ICMA)

• 10 = actual/365 (ICMA)

• 11 = 30/360E (ICMA)

• 12 = actual/365 (ISDA)

• 13 = BUS/252

For more information, see Basis.

Data Types: double

(Optional) Notional principal amount, specified as a NINST-by-1 of notional principal amounts, or a NINST-by-1 cell array, where each element is a NumDates-by-2 cell array where the first column is dates and the second column is associated principal amount. The date indicates the last day that the principal value is valid.

Use Principal to pass a schedule to compute the price for an amortizing cap.

Data Types: double | cell

(Optional) Derivatives pricing options structure, specified using derivset.

Data Types: struct

## Output Arguments

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Expected price of the cap at time 0, returned as a NINST-by-1 vector.

Tree structure with values of the cap at each node, returned as a MATLAB® structure of trees containing vectors of instrument prices and a vector of observation times for each node:

• PriceTree.PTree contains cap prices.

• PriceTree.tObs contains the observation times.

• PriceTree.Connect contains the connectivity vectors. Each element in the cell array describes how nodes in that level connect to the next. For a given tree level, there are NumNodes elements in the vector, and they contain the index of the node at the next level that the middle branch connects to. Subtracting 1 from that value indicates where the up-branch connects to, and adding 1 indicated where the down branch connects to.

• PriceTree.Probs contains the probability arrays. Each element of the cell array contains the up, middle, and down transition probabilities for each node of the level.

## More About

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### Cap

A cap is a contract that includes a guarantee that sets the maximum interest rate to be paid by the holder, based on an otherwise floating interest rate.

The payoff for a cap is:

$\mathrm{max}\left(CurrentRate-CapRate,0\right)$

For more information, see Cap.

## Version History

Introduced before R2006a

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