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Natural logs are
frequently used in finance. |
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B |
C |
D |
E |
F |
G |
H |
I |
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The compound value of a $
is: |
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V = P *(1+ i/n)^(n*t) |
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where: |
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V is the ending value |
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P is the present value
you start with |
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I is the rate of interest |
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n is the frequency of
compounding |
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t is the length of time |
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Notice that part of the
formula looks a lot like the expansion to get the value of "e" |
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If we let P=1 and t=1 it
is exactly the same formula. |
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V = 1 *(1+ i/n)^(n*1) |
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If n =1 then we get: (which is frequently the form of the
compound amount formula) |
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V = P *(1+ i/1)^(1*t) |
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Impact of compounding |
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Using an interest rate
of: |
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5.0000% |
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Assume the time period is
1 year and the amount is $1 |
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Frequency of compounding |
n |
V |
Annual Rate of return |
ln(Annual Rate of Return) |
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Annual |
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1 |
$1.05000 |
5.0000% |
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4.8790% |
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Semi-Annual |
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2 |
$1.05063 |
5.0625% |
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4.9385% |
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Quarterly |
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4 |
$1.05095 |
5.0945% |
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4.9690% |
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Monthly |
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12 |
$1.05116 |
5.1162% |
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4.9896% |
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Daily |
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365 |
$1.05127 |
5.1267% |
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4.9997% |
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Hourly |
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8760 |
$1.05127 |
5.1271% |
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5.0000% |
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Minutely |
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525600 |
$1.05127 |
5.1271% |
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5.0000% |
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Secondly |
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31536000 |
$1.05127 |
5.1271% |
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5.0000% |
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Infinite |
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=EXP(i) |
$1.05127 |
5.1271% |
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5.0000% |
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Notice that as the
frequency of compounding increase our rate of return increase, but at a
decreasing rate. |
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Until the difference
between daily, secondly and infinite is nil. |
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So if you allow infinite
compounding the future value of a dollar formula becomes: |
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V = P*exp(i*t) |
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Remembering that ln and
e^x are opposite transactions we can determine an equivalence between rates
of interest and compounding |
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You
would indifferent between the following rates compounded
once a year, or the rates compounded continuously. |
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Compounded once a year |
Compounded continuously |
Compound amount of $1
at the end of a year |
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Annual Rate of return |
ln(1+Annual Rate of Return) |
Once a year |
Continuously |
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5.0000% |
4.8790% |
$1.0500 |
$1.0500 |
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5.0625% |
4.9385% |
$1.0506 |
$1.0506 |
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5.0945% |
4.9690% |
$1.0509 |
$1.0509 |
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5.1162% |
4.9896% |
$1.0512 |
$1.0512 |
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5.1267% |
4.9997% |
$1.0513 |
$1.0513 |
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5.0000% |
$1.0513 |
$1.0513 |
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You can always find a
rate that will cause you to be indifferent between an annual rate and
continuously compounded one by taking the ln(1+i) |
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Annual Rate |
Continuously
Compounded |
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5.0000% |
4.8790% |
<=LN(1+B78) |
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Or you find a
continuously compounded rate that is equal to an annual rate by using
exp(i)-1 |
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Continuously
Compounded |
Annual Rate |
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5.5000% |
5.6541% |
<=EXP(B83)-1 |
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Try it by changing the green numbers |
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In many cases theoretical
consideration require that we use continuously compounded rates in finance. |
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In
general when using the CAPM and Black/Scholes you should use continuously
compounded rates. |
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