Eduzan

Category: Market Efficiency

  • Semi-Strong-Form Market Efficiency

    In a semi-strong-form efficient market, prices reflect all publicly available information.

    This includes past market data, company earnings, dividends, financial statements, stock splits, merger news, and other public announcements. If the market is semi-strong efficient, investors cannot consistently earn abnormal returns by analyzing public information.

    Example:
    Suppose a company announces earnings of ₹150 crore, while investors expected only ₹120 crore.

    This is positive public information. In a semi-strong efficient market, the stock price may quickly rise from ₹800 to ₹880 as soon as the news is released.

    If an investor buys after the announcement, they may not earn abnormal profit because the price has already adjusted.

    So, semi-strong efficiency means public information is quickly reflected in market prices.

  • Weak-Form Market Efficiency

    In a weak-form efficient market, current prices fully reflect all past market data, such as historical prices and trading volume.

    This means investors cannot consistently earn abnormal returns by using past price trends or chart patterns. Technical analysis becomes less useful because past information is already included in the current price.

    Example:
    Suppose a stock increased from ₹100 to ₹110 to ₹120 in the last three days. A trader may think the price will continue rising because of the past trend.

    But in a weak-form efficient market, this past price movement is already reflected in the current price of ₹120. The trader cannot consistently earn extra profit only by using this trend.

    If the expected return is 8% and the trader earns 8%, there is no abnormal return. Abnormal return exists only if actual return is higher than expected return.

    So, weak-form efficiency says past price data alone cannot be used to beat the market consistently.

  • Forms of Market Efficiency

    Market efficiency explains how much information is already reflected in security prices. Eugene Fama classified market efficiency into three forms: weak form, semi-strong form, and strong form.

    In weak-form efficiency, prices reflect past market data. In semi-strong-form efficiency, prices reflect past data and all public information. In strong-form efficiency, prices reflect past data, public information, and private information.

    Example:
    Suppose a stock is trading at ₹500.

    If the market is weak-form efficient, the price already reflects past price and volume data.
    If the market is semi-strong efficient, the price also reflects public news such as earnings and dividends.
    If the market is strong-form efficient, the price even reflects private information known by insiders.

    So, the stronger the form of market efficiency, the more information is included in the stock price.

  • Active Strategy vs Passive Strategy

    An active investment strategy tries to earn higher returns by identifying mispriced securities. Active investors believe that some securities are undervalued or overvalued and try to profit from these pricing errors.

    A passive investment strategy does not try to beat the market. Instead, it focuses on holding a diversified portfolio for the long term, usually at a lower cost.

    In efficient markets, passive strategies are often preferred because prices already reflect information. Active strategies may not generate enough extra return after considering costs.

    Example:
     Suppose an active fund gives a return of 13% in one year. A passive index fund gives a return of 12% in the same year.

    However, the active fund charges 2% as management fees, while the index fund charges only 0.3%.

    After costs:

    Active fund return = 13% – 2% = 11%
     Passive fund return = 12% – 0.3% = 11.7%

    Even though the active fund performed better before costs, the passive fund gave a better return after costs.

    This is why cost plays an important role in market efficiency and investment strategy.

  • Arbitrage and Market Efficiency

    Arbitrage means buying an asset in one market at a lower price and selling it in another market at a higher price to earn a riskless profit.

    Arbitrage helps improve market efficiency because it removes pricing differences between markets.

    Example:
    Suppose the same stock is trading at ₹100 on Market A and ₹105 on Market B.

    An arbitrageur can buy the stock at ₹100 in Market A and sell it at ₹105 in Market B.

    Profit per share:

    ₹105 – ₹100 = ₹5

    If the arbitrageur trades 1,000 shares, total profit will be:

    ₹5 × 1,000 = ₹5,000

    As more traders do this, demand increases in Market A and selling pressure increases in Market B. Eventually, the prices move closer, and the price difference disappears.

    So, arbitrage helps correct mispricing and makes markets more efficient.

  • Efficient Market and Risk-Adjusted Returns

    In an efficient market, investors should not expect to earn superior returns without taking additional risk.

    If one investment gives a higher expected return, it is usually because it carries higher risk. Market efficiency suggests that prices adjust in such a way that return and risk remain connected.

    Example:
     Suppose a government bond gives a return of 7% per year and a small company stock gives an expected return of 15% per year.

    The higher return from the stock does not mean free profit. It may reflect higher business risk, price volatility, and uncertainty.

    If the stock was offering 15% return with the same risk as the bond, many investors would buy it. This buying pressure would increase the stock price and reduce its expected return.

    So, in efficient markets, higher returns usually come with higher risk.

  • Efficient Markets and Investor Expectations

    In an efficient market, asset prices are influenced by investor expectations.

    Investors form expectations about future cash flows, risk, growth, and required return. When new information arrives, these expectations change. Based on their revised views, some investors buy the asset while others sell it.

    The market price is formed through this buying and selling process.

    Example:
     Suppose a stock is trading at ₹1,000. Investors expect the company to grow at 8% per year.

    Now the company announces a new product launch, and investors believe that future growth may increase to 12% per year. Because of this higher growth expectation, more investors may start buying the stock.

    As demand increases, the stock price may rise from ₹1,000 to ₹1,150.

    This price change reflects the revised expectations of investors.

    So, an efficient market continuously updates prices based on new expectations.

  • Efficient Markets Are Not Always Perfect

    An efficient market does not mean the market is perfect.

    In real life, markets are usually neither completely efficient nor completely inefficient. They often fall somewhere between these two extremes. Some securities may reflect information quickly, while others may adjust slowly.

    Market efficiency depends on several factors such as:

    1. Number of investors following the security
    2. Availability of information
    3. Trading volume
    4. Liquidity
    5. Transaction costs
    6. Speed of information flow

    Example:
     A large company stock may be followed by 50 analysts and thousands of investors. If new information is released, the price may adjust very quickly.

    But a small company stock may be followed by only 2 or 3 analysts. Since fewer investors track it, the price may take longer to adjust.

    This means large and liquid markets are generally more efficient than small and less liquid markets.

  • Expected Information vs Unexpected Information

    In an efficient market, prices react mainly to unexpected information.

    If investors already expect a particular result, that expectation may already be included in the asset price. Therefore, when the expected result is announced, the price may not move much.

    But if the actual result is better or worse than expected, the price may change significantly.

    Example:
     Suppose investors expect a company to report a profit of ₹100 crore. Based on this expectation, the stock is already trading at ₹800.

    Now there are three possible outcomes:

    1. Company reports profit of ₹100 crore
       The stock price may not change much because the result was expected.
    2. Company reports profit of ₹130 crore
       The stock price may rise because the profit is ₹30 crore higher than expected.
    3. Company reports profit of ₹70 crore
       The stock price may fall because the profit is ₹30 crore lower than expected.

    This shows that market prices respond more strongly to surprise information than expected information.

  • Financial Disclosure and Fair Markets

    Financial disclosure means companies share important financial and business information with the public.

    Good disclosure helps investors understand the value, risk, and performance of a company. When disclosure is clear and timely, prices are more likely to reflect true information.

    Example:
    Suppose a company has debt of ₹500 crore, but it clearly discloses this in its financial statements. Investors can include this risk while valuing the company.

    If the stock was trading at ₹1,000, investors may revise the fair value to ₹900 after considering the debt risk.

    But if the company hides important information, investors may make wrong decisions. This can lead to mispricing in the market.

    So, proper financial disclosure improves fairness, transparency, and market efficiency.