Saturday, April 08, 2017

Efficient Market Hypothesis

Financial Markets are influenced by money flows and information flows. In free and highly competitive markets,demand and supply pressures determine the prices or interest rates. In a theoretical sense, markets are said to be efficient, if there is a free flow of information and market absorbs this information fully and quickly.

James Lorie has defined the efficient security market as follows: Efficiency.means the ability of the capital market to function, so that prices of securities react rapidly to new information. Such efficiency will produce prices that are appropriate in terms of current knowledge, and investors will be less likely to make unwise investments.” In the above context, what will happen is that market making mechanism is free and unfettered. There are no pockets with holding information or interested parties making undue gains by insider information by manipulation of supply and demand forces. There will be no monopoly elements and malpractices or corruption etc. are not prevalent. Information flow is free and costless. In the normal course, capital or money flows into areas which are most profitable this in turn depends on their efficiency and competitiveness. Money flows also from less profitable to more profitable avenues if information flow is free, fast and costless. In such market scenario, all investors will have the same information, which is immediately reflected in the stock prices and nobody can gain extra profits. Al instruments in the market will be correctly priced, as all the available information is perfectly absorbed and any investor entering the market any time will have the same advantage or returns. No excess profits are possible in this scenario. As the demand and supply forces are playing their role freely, the emerging prices are fair and move in a random manner. Prices of today are no more a function of the prices in the past as the day-to-day forces move in an independent and random manner. This concept of randomness has led to the theory of random Walk in the determination of prices. This Random Walk hypothesis is thus a special case of the Efficient Market Theory.

For the capital market efficiency theory to operate, the following assumptions are made
1. Information is free and quick to flow.
2. All investors have the same access to information.
3. Transaction costs, taxes and any bottlenecks are not there and not hampering the free forces of market.
4. Investors are rational and behave in a cost effective competitive manner for optimisation of returns.
5. Every investor has access to lending and borrowing at the same rate.
6. Market prices are not stickily and absorb the market information quickly and the market responds to new technology, new trends, changes in tastes, habits of consumers etc., efficiently and quickly.

Random Walk Theory
As per this theory, changes in stock prices are independent of each other. The prices of today are independent of the past trends. The present price is randomly determined and only information flow can influence prices. As information is free and independent, the resulting prices are free and independent. A word of caution is necessary here. This Random walk hypothesis was postulated by researchers on the basis of empirical work on the market price behavior. It does not therefore tantamount to the same theory as the capital market efficiency theory. Only market efficiency promotes randomness and is therefore not a necessary condition. The fact that prices move independently has been found empirically and the analysts found an explanation for this in the efficient functioning of the markets and the market absorption of the information quickly and efficiently. The equilibrium price of a stock is determined by demand and supply forces, based on the available information. Quickly as the fresh information becomes available, a new equilibrium point is reached and the resultant price is thus independent of the part. This Random walk hypothesis contradicts the Chartist and Technical School which believes that the present prices are the result of the past trends and that averages discount all fluctuations and that the average trends move in a predictable manner as the history of trends repeats itself. On the other hand, fundamental school postulates that the prices are a function of the intrinsic value pf the stock and prices result from changes I the intrinsic value and information relating to fundamental factors influence the equilibrium prices. Random walk hypothesis is an offshoot or a phase of the capital market efficiency theorem. The market  efficiency theory postulates that prices are the result of free flow of information which the market absorbs quickly and efficiently.

Assumption of Random Walk Theory
1. Market is supreme and no individual investor or group can influence it.
2. Stock prices discount all information quickly.
3. Markets are efficient and that the flow of information is free and unbiassed.
4. All investors have free access to the same information and nobody has superior knowledge or expertise.
5. Market quickly adjusts itself to any deviation from equilibrium level due to the operation of free forces of demand and supply.
6. Market prices change only on information relating to the fundamentals, when the equilibrium level itself may shift.
7. These prices move in an independent fashion, within undue pressures or manipulation.
8. Nobody has better knowledge or insider information.
9. Investors behave in a rational manner and demand and supply forces are the result of rational investment decisions.
10. Institutional investors or any major fund managers have to follow the market and market cannot be influenced by them.
11. A large number of buyers & sellers and perfect market conditions of competition will prevail;

Random Walk and Efficient Market Theory
Random Walk hypothesis is considered as restatement or a form of Efficient Market Theory by some Analysts. The EM - (Efficient Market Hypothesis) is based on the flow of free and correct information and the market absorption of it. This information flow and its absorption by the market are the critical elements of this theory. There are three types of information affecting the market, namely, Post Prices and trends, other public information and inside information. If all these types are not absorbed perfectly by the market, there is a possibility of some gaining above average returns, from the investments. Based on the above three types of information, the analysis have placed the market absorption and the related theory under three heads; namely :

a. Weak Form of EMH, which absorbs only market price information,
b. Semi strong Form which absorbs price information and also all other public information and
c. Strong Form which absorbs all types of information including insider information.

Weak form of EMH is closely related to the Random Walk Hypothesis, as the past prices are already absorbed by the market and the present prices move therefore independently of the pat, which is the same as the Random walk hypothesis. The present trends are thus random variables, and past data cannot be used to predict the future. All the information on the past data on price trends and volumes was already absorbed earlier. As prices have no memory of the past, yesterday prices have nothing to do with today’s prices. To give an example from BSE quotation Dr. Reddy Labs has yearly low of Rs. 190 and a high of Rs. 333; its price at close on Oct. 15, 1996 was Rs. 215, but it opened on Oct. 16, at Rs. 212 and closed at Rs. 210. A day later it opened again at a higher price, independent of the last closing. It is futile exercise that the present day price can be derived by any past data, at least in short run. If that is proved empirically, then prices move in a random fashion like the walk of a Drunkard, each move independent of the other. It is anybody’s guess or the result of a toss of coin of what will be the price of TISCO today or Dr. Reddy Labs tomorrow. Thus the Random Walk hypothesis states that prices move in random manner, independent of the past prices. In the real world, the weak form of market efficiency may exist, as prices do move in an independent manner which the empirical evidence has shown as the past prices are already absorbed by the market. However, it is to be cancelled that market imperfections, costs of information and blocks to the free flow of information may stand in the way of free play of market forces. peculates and groups of interested parties or even brokers may manipulate the prices through cornering of shares and reducing the flatting stock of the market. Both the Random walk hypothesis and weak form of EMH, state almost the same thing, namely, that knowledge of the past stock price does not aid the investors to gain any improved performance. The prices move independent of the other; although they may move in a random manner they move around a trend line decided by the anticipated real earnings of the company and its fundamentals. Both EMH in weak form and the Random Walk Theory thus postulate that analysing the past does not improve the forecasting ability of stock prices and new information and prices that result from them cannot be predicated.

Empirical Tests
There were several empirical tests on the Random Walk Theory. The question tested was whether the security prices follow a “Random Walk, whether today’s prices are in any way a functon of the past prices. Similarly weak form of Market efficiency also states that no investor can use the price information of the past to earn superior return on investment. Investors who analysed the past fundamentals involving price behaviour of the past did pick up good blue chips in their portfolio, but that did not give them superior portolio Empirical tests were conducted both in the past and the present and in India and abroad on the validity of Random Walk hypothesis. These tests to some extent support the hypothesis that price changes of today are independent of the past price changes. But the evidence is not conclusive and results varied with the time period’s chosen and the data used. Cowles (1934) and JOnes (1937) and Kendall (1953) etc. have shown in their research that security prices moved in a random fashion.

Filter Tests
Filter tests are based on the principle of fixing a filter level varying from 0.5% to 5%, and then examine how well pick up both trends and reversals. Thus, if a stock moves up a filter point say 5%; then buy it and hold it long; when it reverses by the same filter point, 5%, sell it and take a short position in it. A short position is one where on sells even without holding shares to deliver. When the stock price reverses again at the filter point, cover the short position by buying the shares in the market. By this process, the contention of chartists that prices and volume data of the past are supposed to tell the entire story and our approach is to forecast the trends and reversal only. Filtering is the screening of the important information affecting the prices from unimportant and see how well the price changes pick up the trends and reversals. The results of tests conducted by Fama, Blume and Alexander on the basis of filter points also did not give conclusive proofs. If the filter level is low, the market swings capture these levels, but if the filter level is taken to be large, then results did not prove the hypothesis. Even in case of smaller filters, if transaction costs and other charges are taken into account the investors did not profit by using the filter tests. In sum, the results of filter tests did not prove the chartist school’s validity. Stock prices do not move in a predictable fashion of movement and reversals and one cannot make return in excess of the results warranted by the risks assumed by the investors. These results prove that the weak form of market efficiency holds good as it is not possible to gain more from the price information of the market.

Serial Correlation Tests
Mr. Moore tested the movement of stock prices through serial correlation tests. Serial correlation is used to measure the extent of association of one series of security prices with a series in the past. Moore measures the correlation coefficient of price changes of one week with the price changes a week later and so on down the line. Its results showed that the correlation coefficient is very low indicating that a price rise did not show the tendency to the price fall and vice vers in any predictable manner. The price changes of this week do not therefore depend on the past price changes to any significant extent. Fama did the same correlation tests on daily price changes in 1965. He studied the companies included in the Dow Jones Industrial average for five years. His research showed low correlation and this proved that there is no significant relation between price changes in successive periods. Serial correlation or auto correlation of price data of different time periods did not show significant positive results. This proves that prices move in an independent fashion to a large extent.

Run Tests
A run is a set of consecutive price changes in the same direction. The time series data on price changes of stocks are used to test whether there are dependencies among these series in terms of signs and reversal of signs. Fama made Run Tests to examine whether the price changes were likely to be followed by further price changes in the same direction. Run tests are conducted by the following method :

Example Elecon Engi
Suppose the price changes are as follows : Rs. 40, 40.5, 41.50, 41.5, 45.0, 44.0, 44.0, 44.5, 46.0, 45.0 – 10 observations for ten days, then count the number of consecutive signs in the same direction which will have (+) sign. Then count the number of signs with no change with a zero sign and those with consecutive price declines (with Minus sign). In the above example we have two positive, two zero sign and then one positive, one negative sign, two with zero sign and two again the positive sign and the last with a negative sign. These data show that there are no price dependencies. Yesterday’s prices neither tell us of today’s price nor today’s price of tomorrow's price. There is no consistency in the price changes. This conclusion also gives support to Random Walk hypothesis. Hagerman and Richmand made a similar study for prie changes observed on securities traded on O.T.C. (Over the Counter). The efficiency of options Market was tested by Black and Scholles. Their research showed that the market was not perfect and that the transactions costs are so high that those tradign in the market could not make abnormal returns. Granger and Morgenstern used a method known as Spectral Analysis in 1963 to test the Random nature of the stock prices. They did not notice any worthwhile relationship between the returns of security in one period and the returns in the previous periods. Most of these research results proved that security prices moved in a random manner and are not amenable to any precise forecast.

Other Tester
Brownian motion in physics is a kind of Random Walk. The research conducted by Osborne showed that stock prices moved in a Brownian fashion. This means that simulation tests conducted by some authors showed that the mechanism of Random Walk generated variables which are similar to movement of stock prices. Robert’s research in simulation tests in particular confirmed that price changes in the present period are independent of the past trends. Research conducted by Levy in 1967 and be Jensen and Bennington in 1970 and many others did not find any significant abnormal returns due to a study of past price and volume data used in portfolio selection.

Mutual Fund Performance
Similarly mutual fund performance based on insider information is also not found to bear any superior returns. Friend in 1972, Sharpe in 1966 and Jensen in 1969 studied relative performance of mutual funds. It was for that their results are no better. The hypothesis tested and found void is that mutual funds could earn extra ordinary returns and constantly achieve a higher average performance, because they have better access to insider information. Research studies made by Blume, Williamson and others in this line proved that the mutual-fund performance was not extra ordinary or superior to average market performance. They have probably no insider information or their expertise is not superior or their administrative costs are higher than for individuals.

Efficient Market Hypothesis
As referred to earlier, there are three forms of the Hypothesis, namely, weak form of EMH discussed under Random Walk Theory, semi strong from and strong form. In the words of Fama, efficient market is defined as the market where there are a large number of rational profit maximisers actively competing with each trying to predict the future market and where the current information is almost freely and equally available to all participants. Analysis of the Research studies done so far confirm partly the weak form of EMH. But the other two forms of the Theory are found not really realistic in the Practical Market Scene.

Semi Strong Form of EMH
This form of EMH postulates that the market absorbs quickly and efficiently not only the price information but all publicly available information. Examples of this public information are found in the Financial reports, Balance Sheets and Profit and Loss Accounts, Earnings and Dividend Reports, financial results etc. In addition to financial data, any material information affecting the financial position, such as financial structure, liquidity, solvency etc. is also found relevant and absorbed by the market in the price formation. Some data and information may be contradictory and biased information, rumours etc. would also flow in as news affecting the market. Revision of data or changes in conditions of the company also affect the price. Studies on the time lag involved in the impact of any change of fundamentals on the company share price showed varied time lags, some being discounted even before the event is announced and some before the event took place. Such matters like earnings reports, bonus, rights affect the market even in anticipation before the formal announcement. The studies on the semi strong form of market efficiency related to the effect of any public information released, on the share price . The tests are invariably based on pricing models, as  under the CAPM or some economietric models. These studies showed that the absorption of this information on share prices was inefficient and varied from scrip to scrip, and the time period studied. The inefficiency in the market mechanism absorbing this data is found to be corrected over a time period as investors take time to analyse and conclude the effect of any public information. Thus, the semi strong form is empirically not well supported, but in many foreign markets, the semi strong form is found to be applicable and markets quickly absorb all published information. This is possible in those markets due to strict law enforcement, bu the market authorities, instantaneous display of all market information through electronic media and investor awareness of their impact and their quick absorption of the data. The revolution in informatics and communication technologies has made it possible for the application of the semi strong form of the EMH to these markets in developed countries.

Strong Form of EMH
Under this hypothesis markets are so perfect that all information including private information, insider information and unpublished data, affecting the market are absorbed in the stock prices. Any investor can then gain the same average returns, whenever he entries the market. The information of all types is flashed to all investors simultaneously and all players have the same information at the same time. This means that only superior analysis and interpretation can give better market returns. This is possible for inside traders, floor brokers and institutional investors who have highly efficient market research component. The acumen with which price movements can be forecast can only result in superior return and not otherwise. Studies made in developed markets have showed that strong form of efficient market does not exist there also. Investors have not shown consistently higher returns seen with all the information available to them. It was also found that average investor could do better by picking up securities in a random fashion.

Markets in India
It will thus be seen that the EMH in its strong form is not realistic in the actual markets. In India, in particular, despite all best efforts of SEBI, market prices are rigged up, and it is common to notice various price behavioural patterns and manipulation of prices. Information is costly and time consuming. No unqualified empirical support is found for efficient market hypothesis, even in its weakest form in India. In the case of institutional investors, equity market research is a tool used for forecasting prices and identification of undervalued scrips through fundamental analysis and determining the timings for purchase and sale by technical analysis, Although the followers of Technical or Chartist methods are very few in India, the major component of market research revolves around both fundamental and technical factors. In practise, therefore many of these Theories, including the random walk theory are inapplicable to Indian conditions. Speculation is as high as 70-80% in Indian markets and markets are not perfect and the absorption of all types of information is also not timely and efficient. The investors in India go by research into fundamentals and select the scripts on the basis of their assessment of the extent of overvaluation and under valuation. Investment analysis therefore only involves the market research, fundamental analysis to a great extent and technical analysis to lesser extent with a view to select the undervalued scrips in the context of market conditions, reflect in the sentiment and psychology of the market.

Critique of EMH
Opinion is divided as to the validity of the EMH particularly in the strong form. In weak form Random Walk hypothesis holds good, as per some studies. The semi strong form has found less support from the empirical studies. The perfect markets do not exist, as the stocks as a rule do not sell at the best price based on intrinsic values. Many times, speculative fervour sentiment and expectations play a greater role on the stock prices than the fundamental factors. Similarly news does not spread evenly among all segments of the market and among all investors. Institutional investors gain through market equity research and through economic of scale and better expertise. But individual investors do not gain by speedy spread of information and the absorption of the same by market. To gain, superior advantage, there was no adequate evidence from any of the empirical studies, based on prices or information. There is thus a controversy on the validity of Efficient Market Theory. In real market operations, this theory did no find support, as portfolio managers did not perform better based on the results of this theory. This theory posed a challenge to both the chartist school and the fundamentalist school. If Random Walk or Weak Market Efficiency holds good, chartist school finds its tools are not of real value to gain superior returns. Similarly if random walk holds good, chartist school finds its tools are not of real value to gain superior returns. Similarly if random walk holds good, following the study of fundamentals will not secure better returns, unless additional information and insights into the company or better insider knowledge are available to investors

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