Convexity: Difference between revisions

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== Broad definition of convexity ==
Convexity measures the curvature of the profile representing the relationship between an instrument’s or a portfolio's yield and its value. 


Broadly, convexity measures the curvature of the line representing the relationship between an instrument’s yield and its value. 


Duration and Modified duration can be used as the basis for straight line estimates of the rate of change of price/present value.  Convexity is an estimate of the rate of change of duration. 
Convexity is normally calculated as:


This is often visualised as the degree of 'curviness' of the line representing value versus yield.
'''Sum [PV x t x (t+1)]/Sum(PV)'''.


Convexity is calculated as:


'''Sum [PV x t x (t+1)]/Sum(PV)'''.
Where:
 
PV = Present Value of individual cash flows
 
t = timing of cash flows


== Stricter definition of convexity ==


More strictly defined, convexity is the rate of change of duration, and modified convexity is the rate of change of modified duration, for small changes in yield from the given starting yield.
Strictly defined, convexity is the rate of change of duration, and [[modified convexity]] is the rate of change of modified duration, for small changes in yield from the given starting yield.


== Looser definition of convexity ==


More loosely, the terms ''Convexity'' and ''Modified convexity'' are often used interchangeably.   
More loosely, the terms ''Convexity'' and ''Modified convexity'' are sometimes used interchangeably.   


Obviously this can lead to potential confusion, so it is important to clarify whether convexity or modified convexity is intended in any particular context.
Obviously this can lead to confusion, so it is important to clarify whether convexity or modified convexity is intended.


== See also ==
== See also ==
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* [[Modified convexity]]
* [[Modified convexity]]
* [[Modified duration]]
* [[Modified duration]]
[[Category:Interest_Rate_Risk]]
[[Category:Managing_Risk]]

Revision as of 08:55, 29 July 2014

Convexity measures the curvature of the profile representing the relationship between an instrument’s or a portfolio's yield and its value.


Convexity is normally calculated as:

Sum [PV x t x (t+1)]/Sum(PV).


Where:

PV = Present Value of individual cash flows

t = timing of cash flows


Strictly defined, convexity is the rate of change of duration, and modified convexity is the rate of change of modified duration, for small changes in yield from the given starting yield.


More loosely, the terms Convexity and Modified convexity are sometimes used interchangeably.

Obviously this can lead to confusion, so it is important to clarify whether convexity or modified convexity is intended.

See also