What is an Investment Theory? Overview, Definition, 6 Facts

The idea of investment is one of the oldest economic theories. This theory addresses the investment of economic resources. The theory is vitally important to all economists, but identifying the best investment possibilities is crucial.

What is an Investment Theory?

A theory of investing is a notion that takes into account a variety of elements related to the investment process. Ideally, the theory will include analyzing a broad variety of elements to discover how to choose the most appropriate investments for a specific aim or purpose.

What is an Investment Theory?

Despite the fact that there are ways to investment theory that incorporate a number of different theories as part of the process, some economists divide the work into four categories that virtually anybody can comprehend.

Key Factor in Investment Theory

Goals For The Investment Portfolio

The objectives of the investment portfolio are the first crucial aspect in investment theory. By selecting how to diversify the portfolio while maintaining a balance between diversity and the kind of individual securities, the goal is to shield the investor from declines in one market by allowing for increases in the value of other assets.

This element, also known as contemporary portfolio theory, is crucial to the investment process for investors with defined income targets for their portfolios.

Evaluating Investments

The evaluation of assets based on their level of risk and possible return is an additional crucial part of investment theory.

In this case, the objective is to assist the investor in concentrating on choices that entail an acceptable level of risk and offer the highest return.

This factor is the foundation of the capital asset pricing model and can have a significant impact on whether an investor makes the best portfolio decisions.

The Arbitrage Pricing Theory

A similar approach, known as the arbitrage pricing theory, focuses more on assessing the degree of risk associated with a given investment option, but it still serves the purpose of assisting an investor in determining whether the potential return justifies the volatility associated with a given option.

The Key Element That Make A Good Investment Theory

A well-crafted investment theory will also take into account the quantity of accessible information regarding both the investment option and the market or marketplaces where the option is traded.

This notion, also known as the efficient market hypothesis, states that for a market to be really efficient, all essential information regarding the choice to hold, purchase, or sell an option must be easily available to investors.

Prior to opting to engage in a certain investment, the investor should establish whether or not this condition of an efficient market exists. Knowing the previous history, present status, and potential future hazards connected with any investment is crucial for making good decisions.

What is an Investment Theory?

Special Point

A philosophy of investments is all about making intelligent investment selections. By taking the investor’s goals and objectives into account, it is feasible to construct a portfolio that will help achieve those objectives.

To make intelligent investment decisions, it is necessary to have complete knowledge of the investment and the market on which it is transacted.

Developing an investing theory that incorporates all of these aspects can significantly boost the likelihood of success and help the investor in avoiding investment opportunities that are not in his or her best interest.

Personal Investment Theory

Maehr and Braskamp’s PI model of accomplishment motivation draws on and combines several characteristics from prior conceptualizations of the nature of motivation that are still regarded essential to any explanation and study of motivation, especially in cross-cultural situations.

PI theory is concerned with how individuals choose to invest their time, energy, and skill. PI theory is particularly applicable to the study of how people from diverse cultural origins respond to distinct accomplishment scenarios.

This is because it does not presume that individuals from a certain culture will engage effort in the same accomplishment settings or, if they do, for the same reasons as individuals from other cultures.

PI theory addresses the apparent contradiction between the low assessment of individuals from non-Western cultural groups on achievement tests and their obvious achievement and motivation across a variety of activities, as evidenced by persistence, level of activity, high performance, and continuing motivation in selected areas of behavior.

In addition, PI theory highlights the influence of social and cultural settings in affecting motivational patterns in completing success objectives.

In addition, it is phenomenologically grounded and stresses the subjective meanings of circumstances in light of people’ culturally formed belief systems, such as self-beliefs, perceptions of suitable objectives, and perceptions of available choices for attaining these goals.

PI theory is a social cognitive theory because it posits that the major antecedents of choice, persistence, and fluctuations in activity levels are ideas, perceptions, and beliefs that are rooted in cultural and social views about the self and the circumstance.

Specifically, the PI theory identifies three fundamental meaning components as crucial to identifying PI in certain situations:

Self-beliefs, refers to the more or less ordered collections of perceptions, beliefs, and emotions associated with one’s identity.

Perceived objectives of conduct in specified contexts, relating to the motivating emphasis of action, namely what the individual defines as success and failure in these situations (e.g., task, ego, social solidarity, extrinsic rewards)

Perceived options for achieving these goals, referring to the behavioral alternatives that an individual thinks to be available and acceptable (in terms of sociocultural norms that exist for the individual) in a particular scenario.

What is an Investment Theory?

Each of these components of PI theory may be variously impacted by the structure of activities and circumstances, personal experience, availability to information, and, most significantly, the sociocultural framework in which tasks, situations, and people are immersed.

As a model, PI theory mitigates a number of the issues inherent to monocultural research methods. Particularly, it conceptualizes success motivation in terms that acknowledge the potential of culturally distinct patterns of accomplishment behavior.

PI theory also seeks a balance between personality and circumstance, adding characteristics (such as locus of control) that have been effective for understanding accomplishment motivation.

In 1995 and 1997, McInerney and colleagues conducted research demonstrating the use of PI theory in cross-cultural situations.

7 Controversial Investing Theories

1. Efficient Markets Hypothesis

The efficient markets hypothesis (EMH) is still debatable. According to the EMH, the market price of a share integrates all available information about that stock. This indicates that the stock’s valuation is accurate until a future event alters it.

Due to the unpredictability of the future, EMH adherents are considerably better off having a diverse portfolio of companies and benefitting from the general growth of the market.

You either believe in it and adhere to passive, broad-market investment techniques, or you despise it and concentrate on selecting stocks based on growth prospects, undervalued assets, etc.

Warren Buffett and other investors who have repeatedly outperformed the market by identifying irrational prices inside the general market are cited by opponents of the EMH.

2. Fifty-Percent Principle

The fifty-percent principle predicts that, prior to continuing, an observable trend will have a price correction of between fifty percent and two-thirds of the price change. This suggests that if a stock has been on an upward trend and gained 20%, it will drop 10% before resuming its ascent.

This is an extreme example, as this rule is often applied to the short-term trends on which technical analysts and traders buy and sell.

This correction is seen to be a natural part of the trend, as it is typically produced by investors taking gains early in order to prevent being caught in a real trend reversal later on. If the correction surpasses fifty percent of the change in price, it is regarded an indication that the trend has failed and the reverse has occurred early.

3. Greater Fool Theory

The larger fool hypothesis posits that you may profit from investing as long as a greater fool than yourself is willing to pay a higher price for the investment. This means that you may be able to profit from an overpriced stock if someone is ready to pay more to purchase it from you.

As the market for any investment overheats, eventually there are no more idiots left. According to the principle of the larger fool, investors should disregard valuations, earnings reports, and other statistics.

What is an Investment Theory?

After a market drop, those who subscribe to the bigger fool idea might be left holding the short end of the stick if they choose to disregard evidence.

4. Odd Lot Theory

The odd lot hypothesis utilizes the selling of odd lots, which are tiny blocks of equities held by individual investors, as a signal of when to purchase a stock.

Investors that adhere to the odd lot principle purchase shares when smaller investors sell. The fundamental premise is that small investors are typically in error.

The odd lot hypothesis is a contrarian investment approach based on a fairly straightforward method of technical analysis — tracking odd lot sales.

Whether an investor or trader following the idea investigates the fundamentals of the firms it recommends or simply buys blindly has a significant impact on his performance.

Small investors won’t always be right or incorrect, thus it’s crucial to differentiate between odd lot sales caused by a low risk tolerance and odd lot sales caused by larger concerns.

Individual investors are more mobile than large funds and may thus respond to bad news more quickly; hence, odd lot sales may be a forerunner to a larger sell-off in a failing business rather than a simple error on the part of small investors.

5. Prospect Theory

Loss-aversion hypothesis is another name for the prospect theory. According to prospect theory, individuals’ views of gain and loss are biased. In other words, individuals are more discouraged by a loss than by a gain.

If individuals are offered a choice between two opportunities, they will go for the one that they believe has a lower likelihood of resulting in a loss, rather than the one that provides the greatest potential for profit.

What is an Investment Theory?

For instance, if a person is offered two investments, one that has returned 5% annually and another that has returned 12%, lost 2.5%, and returned 6% in the same years, he will choose the investment that has returned 5% annually because he places an irrational amount of weight on the single loss, while ignoring the gains that are of greater magnitude. After three years, both solutions in the above illustration provide the same net total return.

Financial experts and investors must understand prospect theory. Despite the fact that the risk/reward trade-off provides a clear picture of the amount of risk an investor must assume in order to attain the desired profits, prospect theory suggests that few individuals comprehend emotionally what they grasp academically.

The issue for financial experts is matching a portfolio to a client’s risk profile, not their reward preferences. For the investor, the issue is to overcome the disillusioning forecasts of prospect theory and develop the courage to achieve the desired profits.

6. Rational Expectations Theory

The rational expectations theory asserts that economic actors will act in accordance with what may be expected rationally in the future.

In other words, a person will invest, spend, etc. according on what they logically anticipate will occur in the future. This produces a self-fulfilling prophesy that aids in the realization of the future occurrence.

Although this idea has been fairly influential in economics, its usefulness is questionable. For instance, if an investor believes a stock will rise, and then purchases it, this action really causes the stock to rise. The identical transaction may be conceptualized independently of rational expectations theory.

An investor recognizes that a stock is undervalued, purchases it, and then observes as other investors do the same, driving the price up to its correct market value. This illustrates the fundamental flaw of the rational expectations theory: it may be altered to explain everything, but it provides no insight.

7. Short Interest Theory

At first look, the idea of short interest, which argues that significant short interest precedes a price increase, appears to be false. A company with a large short interest – that is, a stock that many investors are short selling – is likely destined for a correction, according to common sense.

The argument is that traders, thousands of specialists, and individuals who scrutinize every shred of market data cannot all be incorrect. They may be partially correct, but the fact that the company is extensively shorted may cause its price to climb.

What is an Investment Theory?

Short sellers must eventually cover their holdings by purchasing the borrowed shares. Therefore, the share price will rise due to the purchasing pressure caused by short sellers covering their bets.


We have explored a variety of ideas, ranging from technical trading theories such as short interest and odd lot theory to economic theories such as rational expectations and prospect theory.

Every theory is an effort to impose some form of structure or consistency on the millions of daily buy-and-sell choices that cause the market to rise and fall.

While knowledge of these ideas is beneficial, it is essential to realize that no single theory can adequately describe the financial world.

 During specific time intervals, one hypothesis appears to be dominant, only to be supplanted shortly thereafter. In the financial world, the only genuine constant is change.

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