Friday, June 22, 2007

Risk Adjusted Return - Sharpe Ratio using MS excel sheet free

(Here is a sample Excel sheet to compute the Risk adjusted Return using Sharpe ratio if you directly want to go to the mathematics)

A ratio was developed by Nobel Laureate Bill Sharpe to measure risk-adjusted return of an investment. It is calculated by subtracting the risk-free rate from the rate of return for a portfolio and dividing the result by the standard deviation of the portfolio returns. Or,

Sharpe Ratio = Excess return over risk free return/ Annualized standard deviation of returns

The Sharpe ratio tells us whether the returns of a portfolio are due to smart investment decisions or a result of excess investor risk. This measurement is very useful because although one portfolio or fund can reap higher returns than its peers, it is only a good investment if those higher returns do not come with too much additional risk. The greater a portfolio's Sharpe ratio, the better its risk-adjusted performance has been. A lower number is worse.

Stocks have performed better, on a risk-adjusted basis than Treasury Bonds, because the Sharpe Ratio on stocks is higher than Treasury Bonds. A negative Sharpe Ratio is considered very bad. It means you could have done better, on a risk adjusted basis, by holding cash. The point of risk adjusted return is not to look at return in a vacuum, but rather to consider how much risk you had to take in order to generate "excess return" - the amount of return over a market benchmark or the risk free rate i.e. 10 year Treasuries or 90 day T-bill.

Volatility, also known as the standard deviation of return, is the statistical measure of risk in a portfolio. A standard deviation of zero would mean an investment has a return rate that never varies, like a bank account paying compound interest at a guaranteed rate. (Definition: Standard Deviation is a statistical measure of the distance a quantity is likely to lie from its average value. In finance, standard deviation is applied to the annual rate of return of an investment, to measure the investment's volatility, or risk.)

Here is an example:

Say you have an investment portfolio, You can calculate the value of your investment account periodically, say every month.

Then calculate the average monthly return over some number of months, by averaging the returns for those months. You also calculate the standard deviation of the monthly returns over the same period. Note that you might need data for few months to calculate the standard deviation.

Then annualize the numbers by:

- Multiplying the average monthly return by 12

- Multiplying the standard deviation of the monthly returns by square root of 12

You also need a number for the "risk-free return" which is the annualized return currently available on "risk-free" investments. This is usually assumed to be the return on a 90-day T-Bill (currently about 5% per year)

You now calculate the "Excess return" which is the annualized return achieved by your investment in excess of the risk-free rate of return available. This is the extra return you receive by assuming some risk. Then the Sharpe Ratio is calculated as:

Sharpe Ratio = [Annualized annual return - Risk free return] / Annualized standard deviation of returns;

Here is how you can use Microsoft Excel to calculate Sharpe Ratio for your portfolio. Fill out each column in the excel sheet as follows:

You can see a sample calculation of Sharpe ratio in excel sheet here.

- Column A: Fill out Month Name
- Column B: Beginning Balance
- Column C: Ending Balance
- Column D: Monthly Returns = ((C/B)-1)*100 (to get %)
- On cell E2: Get the average of all monthly returns. E2 = AVERAGE(populated cells from column D)
- On cell E3: Annualized returns = E2 * 12;
- On cell F2: Get the Standard Deviations for all months. F2 = STDEV(populated cells from column D)
- On cell F3: Annualized standard deviation = F2 * SQRT(12);
- On cell G2: Get the 3 month treasury bill from www.ustreas.gov, lets say it is 5%
- On cell G3: Sharpe Ratio = (E3 - G2)/F3

Given all this data, you can strive to achieve higher Sharpe Ratio for your portfolio. Or if your Sharpe Ratio is low, then you can figure out where to fix it.

-Nidhi

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14 comments:

Asif said...

I had considered writing a post about the Sharpe ratio on my blog but you have already done a great job. Moreover the instructions on calculating the Sharpe ratio using excel was very useful.

Asif
www.SINLetter.com

Anonymous said...

Hi, I found your blog when I was trying to calculate the sharpe ratio. It's very useful. Thank you!

I have a question about the "3 Month Treasury Bill" in cell G8. How did you get 0.8% from the risk free return of 5%?

Thanks!

Pi said...

hey nidhi.. nice work.. pleasently surprising to see indian girl blogging online about investing and related things, and that too monetizing it using adsense.that's not to undermine women in any way. just that i havnt seen one such case before.. cool.

so where are u frm ? and also.. is adsense making decent money for u?

Prepared Investor said...

You can find the 3 mon treasury bill rate at:

http://www.ustreas.gov/offices/domestic-finance/debt-management/interest-rate/yield.shtml

Anonymous said...

I apologize. I know you posted that you went to the link mentioned below to obtain the 3 Month Treasury Bill. However, like the person Anonymous wrote on April 29, 2007; I am confused on how you obtained 0.8% from the risk free return of 5%. Would you mind explaining in detail your steps? I am new to this area.

http://www.ustreas.gov/offices/domestic-finance/debt-management/interest-rate/yield.shtml

Thank you in advance.

Anonymous said...

I would suggest to use STDEVP rather than STDEV. Also, I would compute the geometric (GEOMEAN)mean rather than the average. The Sharpe Ration number will change slightly as a consequence.

Anonymous said...

I would suggest to use STDEVP rather than STDEV. Also, I would propose to compute the geometric (GEOMEAN)mean rather than the average. The Sharpe Ratio number will change slightly as a consequence. It is more correct this way.

preparedinvestor said...

The link changes to data for each month, and hence when you visit next time it is on different month's data. FOr May of 2009, here is the data for 5/1/09:

Date 1 mo 3 mo 6 mo 1 yr 2 yr 3 yr 5 yr 7 yr 10 yr 20 yr 30 yr
05/01/09 0.06 0.16 0.31 0.49 0.92 1.39 2.03 2.72 3.21 4.14 4.09

So 3 month data is 0.16. Hope that helps.

preparedinvestor said...

Thanks for the feedback on STDEVP. Let me look into that.

Nidhi

Anonymous said...

Hi,
Nice work on the Sharpe Ratio. Getting the yield on the US Bond market is easy .

From where I can get the 90-day Treasury bill of Govt. Of India .

Anonymous said...

Also, I would compute the geometric (GEOMEAN)mean rather than the average.

But doesn't that only allow positive numbers meaning it will fall over if any return is negative?

Anonymous said...

Dear Author www.thepreparedinvestor.com !
In my opinion you commit an error. Let's discuss it.

rabih said...

i think there's a mistake in cell G6. u have put square root of 12, times SD. r u sure??? if its true, plz elaborate. thanks

Nidhi said...

Rabih,

When you calculate monthly standard deviation, then we can annualize that by multiplying the std dev by square root 12. Similarly if the SD is calculated for daily, then annualization is done by my multiplying daily SD by square root of 250. Assuming 250 is the number of trading days in a year .. hope that helps ..

Basically you are extending monthly variance to yearly and so you multiply by 12. But since you are considering SD, you make it square root of 12.

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