Tuesday, 14 August 2007

(2)-Stock Picking Parameters and Techniques: Continued – Part II

This is part II of the article Stock Picking Parameters and Techniques: Continued – Part I. Please read the first part before proceeding with this one


So, we look at maximizing the RETURN component and minimizing the RISK component. Hence, we take the so-called Sharpe Ratio, which is defined as (Return divided by Risk) or (Average/Std. deviation *100). Since we aim to maximize the returns and minimize the risk, we look for a higher value of Sharpe ratio.

In this case, Satyam has a Sharpe Ratio of 6.3% while Infosys has a Sharpe Ratio of 5.45%. This means that historically, over the past one month, Satyam has been better than Infosys in terms of Return and Risk.

Another thing to note is that the returns of Satyam (0.18%) is double than that of Infosys (0.09%). However, Risk of Satyam is also higher (2.8%) to that of infosys (1.67%).
This also confers with our “High return, High Risk” concept.

So, in essence, looking at Sharpe ratio will give a pretty good idea of what the stock has been doing and how volatile or stable it has been. The calculations can be stretched for years and decades, and the percentage returns can be calculated on weekly, monthly, quarterly or annual basis. A simple rule that is followed is match the historical period with your investment horizon. Meaning, if you want to invest for 3 year long horizon, make calculations for past 3 years.

You can do this calculation for any stock, any Mutual fund or index fund or ETF, or virtually any instrument that your want to anlayse.

However, Sharpe ratio is not fool-proof. The biggest problem is that the calculations are based on historical prices and there is no guarantee that the same will be performed over next horizon in future. But as compared to other figure like EPS, balance sheet calculations, etc. this makes more sense because it is calculated from the market prices. The figures presented in reports and balance sheets can be goofed up, while the market pricing give a better precise estimate.

Ultimately the call is yours. Hundreds of parameters are used in the world of finance. Sharpe Ratio is just one of them and has been effective atleast in terms of estimating the market fluctuations and returns over historic periods. Personally, instead of getting into stocks, I would prefer ETFs, as the standard deviation (risk) of ETF is pretty low compared to stocks. Sharpe ratio of an ETF would be better than that of individual stocks. Moreover, ETFs will never go bankrupt, the individual stocks may be out of business.


A note for equity investors: It has been historically proven that equities give better returns in the long run. So go ahead and invest in equities (Stocks, Mutual Funds, Index Funds, ETFs, etc) as per your need and risk appetite. I am NOT advising you to stay away from them. What I am advising is that set a target and an investment horizon. Exit when the target is achieved, don’t be greedy as that may result in losses.
For e.g., say you want to plan for your retirement and have an investment horizon of 30 years. You are ready to take the risk in stocks and want to invest 1 Lakh each year. So for 30 years, your total investment would be 30 lakhs. Suppose you target a maturity value of 2 Crore Rs. at the end of 30 year long horizon. Suppose, due to excellent Bull Run in the stock market, you managed to reach the target in just 20 years time. At this time, exit from the stock market. Don’t keep on accumulating money in stocks. Take the 2 crore out of stocks and put it in the bank and let it earn bank interest. Atleast your retirement income of 2 crores is safe. This will prevent you from the situation that may collapse the value of your stock investments in case the price fall sharply in last few years of your investment horizon.
For the remaining 10 years, keep on investing your 1 lakh in stocks and let it be exposed to market pricing. Atleast your retirement money of 2 crore will be safe.

That is what is required in investment – Purpose based investments, and target based capitalization. It is tempting to carry on investments in equities when you see that it is growing leaps and bounds – target of 2 crores reached in just 20 years as compared to the estimated 30 years. The failure & loss comes due to greed as there is uncertainty about the investment horizon and when to exit. Have a target in mind and things will work smoothly.


Keep visiting this blog for further content.

Please read the comments and post your views and queries in the comments section which helps in open discussion and avoid duplicity of questions.

You may be interested in reading my previous articles. Here is the link to Table of Contents in a chronological order.

8 comments:

Anonymous said...

Thanks GURU!
Really appreciate your efforts

Keep going.

Aniruddha said...

Hi Shobhit,
It's really nice article on Stock picking parameters. while reading about Sharpe Ratio, one question comes in my mind that, for the calculation we have considered 3 yrs horizon then how you are going to take account of Bonuses, splits or any other external event like Right issue, which brings down stockprice significantly. Like we say xyz is available 30% discount price after Ex bonus...

Thanks
Aniruddha

IT Correspondent said...

That is very good point Aniruddha. I missed that, thatnks for informing me.

When you download the data for historical prices, you must make sure that you download the right data.
For e.g. downloading data from NSE website will give you raw data - meaning it will just give you prices. It does not take into consideration about rights issue, stocks splite, bonus etc.
But when you download teh data from Yahoo Finance website, there you get an additional data column titled "Adjusted Close Price". This price value is adjusted for all kinds of dividend payments, rishts issue, stock splits etc.

So you have 2 choices:
Either download the adjusted price data from a reliable source
OR download raw data, and adjust it for all the corporate actions that may have taken place during the investment horizon

Thanks,

Anonymous said...

Hi Shobhit,
Its very nice to read your articles. From last 3days i've read all your articles from the begining.I came to know about many things which i am not aware.
From many days i was searching for a good resource where i can get the proper info about investments, now i got your BLOG.
Thank you very much for providing excellent information.
Please keepup the GREAT WORK.

Unknown said...

Hi Shobhit,

In addition to Return and Risk, there is a third factor in every investment - Transaction Cost. But yes, this is not considered in Sharpe ratio.

But not sure if Transaction Cost should be ignored while making investment decisions.

OR does Sharpe ratio assume that these are long term investments, hence low transaction costs and not significant enough ?

IT Correspondent said...

Raghu,

No method is fool-proof, as I've mentioned in my article.
You must take transaction costs into consideration when evaluating shrpe ratio.

Vinod said...

Hello Shobhit!!

well aren't we supposed to subtract the rate of return of any risk-free security from the average rate of returns & then divide it by the standard deviation ?

Thanx

IT Correspondent said...

Yes, strictly speaking in quantitative terms, you should subtract the risk free rate of return.

But the risk free rate keeps on changing over a period. Hence, there are 2 versions of Sharpe Ratio. One in which risk free rate is considered constant and hence not included and other, in which the average or weighted risk free rate is taken and deducted.

This article was an introduction that too for selecting between 2 stocks, hence the risk free rate was not considered. Even if you take that into account, you would get the same result.

Usually, the risk free rate is considered in Sarpe ratio when u have to compare some securitites which are heavily dependent on interest rates.


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