Market Efficiency and Behavioural Finance

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The efficient market is the flea market in which the safeties significantly reflect all possible data accurately and faster. For an active market, the entrepreneur must have several knowledgeable investors that actively analyse and trade the stocks, and data must be widely available to the investors and shareholders. Additionally, various events such as accidents or labour strikes randomly occur, and the investors must react very fast and accurately to the new data. However, Cornell (2018) argues that according to EMH (efficient market hypothesis), data is reflected in the established prices, type and sources of the information, speed and quality with which an active market is reflected in the prices. For example, the more data is included into costs, the more effective a market becomes. Behavioural finance is learning and understanding various biases in the human traits when handling funds. Behavioural economics is a field of study that uses behavioural psychology in making the economic decisions to assist in understanding why different rational individuals often make the irrational decisions during investments and use of money.

According to Hirshleifer (2015), the original ideas that stem from the behavioural finance include herd behaviour, mental accounting, anchoring and believing in being. The actively managed funds (AMF) mainly aim at outperforming their set indices. The AMF outclass the benchmark index because of the deviations from their benchmarks. Therefore, tracking error is applied to determine the degree of variation. For example, high tracking error shows a higher level of the actively managed funds. Passive funds commonly known as index funds purposely copy the index being applied when benchmarking their performance. Nonetheless, these passive funds are not actively controlled hence are characterised by zero tracking error. A competitive and efficient market depends on all these factors for more profits. Therefore, the essay focuses on market efficiency and behavioural finance. Furthermore, the study describes the occurrence of actively managed capital and how it is affected by the validity of market effectiveness.

The Detailed Discussion of Market Efficiency

In microeconomics, market efficiency is outlined as an unbiased estimate of an actual value of the investment. According to Fama (1998), the concept of market effectiveness has become controversial and continues to attract strong views because of the differences between people on how investors approach various investing plans. For example, the efficient market offers better estimate values and the evaluation procedure that justifies the market price. For the active market, the shareholders must perceive all markets as inefficient and very possible to defeat. In their study Kristoufek and Vosvrda (2014) outline that an active market must be liquid and more copious, data prices and accessibility must be made available to the investors. Consequently, the transaction costs must be low. However, if the market is not active, there might be a deviation in the market price from the actual values, and evaluation process will be directed towards attaining the reasonable estimates of the benefits.

According to  Garleanu and Pedersen (2018) market efficiency states that despite failure by investors to have precise data, entrepreneurs are unable to beat the markets. As a result, research on market efficiency examines the significant relationship between the available information and stock prices. Therefore, an efficient market is that which the prices continually and sufficiently reflect the available data and the concepts of effectiveness are viewed as the central of funds. The primary question is that can the investors beat the markets? However, according to predictions by EMH theory, if the market is efficient, it becomes impossible to earn the positive excess returns “to beat the market.”

There are three core economic forces likely lead to market efficiency. They include arbitrageurs exist, the occurrence of independent deviations from determined rationality and when the investors intelligently apply their data. According to Fama (1998), there are three different levels of market efficiency. They include weak, semi-strong, and strong form efficient market hypothesis. Moreover, in their discussions, Thaler and Fama distinguishes two major aspects of EMH (efficient market hypothesis). They are whether the investors can defeat the market and whether the values are correct

The weak form efficiency (WFW) /historical prices

The price of assets, entirely and instantly reflect all data of previous costs. Therefore, the forthcoming variations in rates cannot be foreseen through the other expenses. In weak form, everything becomes random. Additionally, volume figures and past prices are not significant in defeating the market.

In Semi-Strong Market Effectiveness/Publicly Available Data

The price anomalies are identified with adjustment on the stock market. Subsequently, the abnormally more considerable benefits are not consistently earned through the public data. However, Garleanu and Pedersen (2018) argue that there is no information neither private nor public that allows stakeholders and investors to earn the abnormally huge returns. Nonetheless, the asset prices reflect the entire individual and general information entirely. Thus, only those investors with additional private data might have an added advantage on the markets. According to EMH, the stock prices solely reflect publicly accessible data.

Strong form efficiency (SFE)/Private Information

SFE is the market effectiveness in which neither private nor public data is essential in defeating the market. Therefore, the inside info is of little application on the industry. Similarly, the asset prices reflect entirely the whole publicly accessible information (Patel, Savani & Poriya, 2017). Thus, nobody can have the advantage on various markets in forecasting the costs because there is no extra information to offer any benefit to the stakeholders and investors. Based on the analysis, there is excess market volatility, over-reactions of the stock prices and long-term trends that occur for over two years. Moreover, there is significant momentum in the stock values with short-term trends for more than five decades. Therefore, financial markets are more efficient.

 The shareholders are not wholly rational, but they exhibit use of heuristics and biases. According to Patel, Savani and Poriya (2017), the asset prices might adjust unanticipated news in the efficient market through various mechanisms. These include an effective market reaction (EMR) where the costs instantaneously alter to a new data. Second, the delayed reactions (DR) where prices partially amend to the fresh data. Last, overreactions and corrections in which the cost over-adjusts to current data, but ultimately falls to the appropriate value. Fama and Thaler, however, agree on the first aspect “investors cannot beat the market” but severely disagrees on the second aspect.

            According to Fama (1998), EMH is a model that is not entirely true since no model has been proven to be true hence prices be used as good approximates. However, according to Thaler, the prices are not suitable for approximations. For example, the black Monday of 1987 saw the markets adversely crashed and declined by 26% in a day.

Effects of The Validity of an Efficient Market of Actively Managed Funds

Market efficiency is characterised by the positive and negative impact on investors and actively managed funds as described below

Built-in accuracy

The significant implication of the efficient market theory is that shareholders should not have the ability to beat the market since all data used to predict the performance is already established in the stock price. The stock value follows the random walk, thus determined by the current news but not the past stock value investments.


In the efficient markets, costs become random and not predictable thereby making it impossible to discern any investment pattern. Additionally, the random walk of value fails every investment policy that aims at beating the market steadily. However, Cremers et al. (2016) assert that EMH recommends that due to the transactions costs incorporated in portfolio management, it is more profitable for investors to put their money in the index fund.

Increase in Share Prices and Volume

Market efficiency significantly leads to an increase in the share volume and prices of the stock market hence the sustainability of the actively managed capital. The actively managed funds have a 76% dependency on the efficient market for more profitable returns and increased investment (Statman, 2018). However, due to the increase in technology in internal and external markets, there is an increasing level of market competition and investment hence severely changing the direction of actively managed funds to passive index capital. The reason is a failure by active managers of funds to take into considerations the charged subscriptions. The effect shows that the market is too compelling to justify the actively managed funds. However, despite the significant impacts, market efficiency is characterised by challenges. These include the occurrence of anomalies in the stock market.

Discussion of The Behavioural Finance

The behavioural finance (BF) is primarily about learning and understanding various biases that occur in human traits when handling funds. By extensions, the decisions that individuals make about capital is extended to enhance and influence the economy of various nations and firms. According to Dr. Richard Thaler, behavioural finance is a combination of economics and psychology that examines what occurs in multiple markets where different agents continually display human complications and limitations (Thaler, 2010). Thaler elaborates that behavioural finance attempts to explain and enhance the understanding of reasoning standards of shareholders.

 Behavioural finance is important since it helps in optimising choices, predicting financial behaviors and helps in reducing the risks associated with investments. According to Thaler (2010), behavioural finance allows organisations to understand why investors purchase or sell the stocks without performing fundamental analysis, but behave irrationally in making investment decisions. Nonetheless, according to the traditional finance, various financial markets are always presumed to be effective, therefore, suggesting that the stock and asset prices reflect the available public data, and the costs instantly change to mirror the current data.

In his study Shiller (2003) outlines that market effectiveness assumes that the shareholder is more rational, and it is not possible to regularly beat the market through applying any data that is already accessible to the public. As opposed to the philosophy of market efficiency that severely dehumanises stakeholders, behavioural finances continuously proposes the presence of different psychological variables incorporated in spending in various stock markets and offering opportunities for the shareholders to benefit. More significant, the behavioural finance is purposely based on the premise that old finance theories assume that human beings make mistakes and do not consider the explanations in a search to understand the safety returns, but assists in explaining how markets can be ineffective. There are many standard features of behavioural finance as outlined below

Common Elements of the Behavioural Finance

Mental accounting

–This is the new psychological mistake in which the investors take undue threats in a given zone and avoid the additional risks in other regions. According to Fama (1998), the investors who split their investments into lower and higher risk portfolios are subject to the mental accounting because the transactions and time associated with differentiating the two do not add value to their wealth

Loss of aversion

Loss of aversion suggests that shareholders anticipate higher returns while using reduced risks, and is regular with the efficient markets. According to the prospect theory of 1979, the stakeholders overweight the adverse (negative) feelings of the loss incurred compared to the equal percentage benefits. In his study Shiller (2003) outlines that the shareholders fear to lose their profits than losses, thus indicating they are irrational. The investors avoid making decisive actions because they fear that whatever decision they make might be considered as a sub-optimal in hindsight.


Herding is the actual act of copying other peoples’ traits even in the occurrence of unfavourable output. Herding occurs due to many reasons. According to Thaler (2010), these include social pressure and a belief that an observation of the overwhelming majority of the stakeholders is ever right. Due to herding behaviors, the investors are increasingly losing their individuality during the decision making process. Other significant components include optimism, regret and anchoring.

The most common challenge to Fama’s useful market theory originates from the behavioural finance. The behavioural economics takes concerns with two important critical implications of EMH that most shareholders make regular rational decisions centred on the available data. Second, that the market cost is ever right. By refuting Fama’s vital assertion, behaviourists assert that the investors can drive the market values by capitalising on a pricing value efficiencies that are caused by shareholders’ behavioural biases.

 According to Statman (2018), there are different factors of behavioural finance that influence making decisions on market efficiency and investment in different nations across the globe. These include prospectus theory and heuristic factors like availability bias, overconfidence and self-control. In his study  Statman (2017) behavioural finances influence the investment decisions that originates from emotions and prejudices. The behaviors of trading volumes and stock returns are substituted by behavioural economics by measuring the rational expectations with various factors like confidence to help in reducing the economic challenges. Generally, behavioural economics comprehends how people’s emotions are significantly associated with volatility of shared values. Statman outlines that the financial decision making the procedure for every nation is influenced by the recent price fluctuations, wealth maximisation, increased  threats, and social responsibility. For example, individuals show variations in risks due to the difference in their age groups. Therefore, is significant to apply behavioural finance for market efficiency.


A highly efficient market has few safeties that are mispriced; hence there is a higher occurrence of inferior or superior performance among various investors. Thus the firms should consider an excellent performance with reducing risks. Organisations should not invest in inefficient markets because they are associated with many sophisticated shareholders with the ability to identify the mispriced securities since the less active and informed investors will not benefit. Second, firm managers must consider various features that affect behavioural finance and establish mechanisms of mitigating risks associated with any approach. Therefore, companies and individuals should consider investing in active investors than passive shareholders.


The traditional financial hypotheses suggest that shareholders are increasingly and entirely rational. However, the regularity of mental errors implies that stakeholders’ attitudes lead them to illogical decisions. Questioning a belief of the market effectiveness has essentially uncovered the plethora of pieces of evidence that all marketers are irrational, thus the crux of behavioral finance. Market efficiency reduces risks and increases investment. Additionally, it assists firms to examine significant markets with reduced threats. However, the primary challenge to market efficiency if the emergence of behavioral finances that has many risks factors. Therefore, the market can never be wholly efficient and is not due to the natural phenomenon, but as a result of an extensive study and research by the fundamental investors. The market effectiveness has changed the direction of actively managed funds to passive index funds as the managers have failed to account for the fees charged.


Cornell, B. (2018). What is the Alternative Hypothesis to Market Efficiency?.

Cremers, M., Ferreira, M. A., Matos, P., & Starks, L. (2016). Indexing and active fund management: International evidence. Journal of Financial Economics, 120(3), 539-560.

Fama, E. F. (1998). Market efficiency, long-term returns, and behavioral finance1. Journal of financial economics, 49(3), 283-306.

Garleanu, N., & Pedersen, L. H. (2018). Efficiently inefficient markets for assets and asset management. The Journal of Finance, 73(4), 1663-1712.

Hirshleifer, D. (2015). Behavioral finance. Annual Review of Financial Economics, 7, 133-159.

Kristoufek, L., & Vosvrda, M. (2014). Commodity futures and market efficiency. Energy Economics, 42, 50-57.

Patel, P., Savani, J., & Poriya, N. (2017). Semi-Strong Form of Market Efficiency for Dividend and Bonus Announcements: An Empirical Study of India Stock Markets. ANVESHAK-International Journal of Management, 6(1), 108-121.

Shiller, R. J. (2003). From efficient markets theory to behavioral finance. Journal of economic perspectives, 17(1), 83-104.

Statman, M. (2017). Finance for Normal People: How Investors and Markets Behave (Introduction).

Statman, M. (2018). Behavioral Finance Lessons for Asset Managers. The Journal of Portfolio Management, 44(7), 135-147.

Thaler, R. H. (2010). The end of behavioral finance.

August 18, 2023


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