Developed in the late 1950’s by Harry Markowitz, Modern Portfolio Theory was introduced as a means of managing an investor’s financial portfolio. According to Markowitz, an investment portfolio cannot be made up of assets (or investments) that are chosen individually. Before selecting companies to invest in, there needs to be a consideration of how the portfolio as a whole unit will change in price.

As with any investment, there is an understood amount of risk involved. By its vary design, then, there is a direct correlation between risk and reward. Typically, investments that are riskier will bring a higher element of return. Portfolio Theory establishes two possible ways of handling risk and return: If the desired amount of risk is known, then the Portfolio Theory will guide the asset selection process to choose investments with a high level of expected return. If the desired expected return is known, the Portfolio Theory explains the steps in selecting investments that offer the lowest risk.

Similar to a financial investor, while investing in several assets an entrepreneur has usually to optimize his portfolio of products / projects. Hence, Portfolio Theory can be applied in selection of products / projects with either higher returns given the level of risk or with lower risk given the level of return.

Portfolio Theory, then, is a system of diversification. Using precise mathematical equations that determine risk and reward, along with a set of assumptions about investors and the financial markets, the Portfolio Theory provides a process of developing an optimal strategy for diversification.

Major Strategy Frameworks | Portfolio Theory

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In this article, we will look at 1) what is Portfolio Theory, 2) when is the Portfolio Theory useful, 3) components of the Portfolio Theory, 4) creating the Portfolio Theory strategy, 5) using the Portfolio Theory strategy, 6) examples of Portfolio Theory strategy – General Electric.


To understand Portfolio Theory, it is helpful to consider an example: a company that has an oil refinery business. This oil company has several oil fields in its portfolio and tries now to select the oil fields with the highest return given the same level of risk. The returns for oil company are the revenues from oil projects devived from its volume of oil production, the oil price, operating costs to maintain the oil refinery, as well as the initial investment in the starting the oil refinery. On the other side, the risk for oil company contains in the ultimate volumes of oil reserves, the change in the oil price and operating costs, as well as unpredicted additional amount of investment for getting the oil field start producing oil. Using the principles of the Portfolio Theory, the company can let its portfolio of oil refinery be diversified, but optimize it by comparing the oil projects based on return and risk profiles. In this example, oil company can for example define the level of risk, which it can handle and select then the oil fields with the highers returns given this level of risk. In doing so, the company can generate a diversified and optimized portfolio of oil projects. It has then minimized their risk, and maximized their return.

Major Strategy Frameworks | Portfolio Theory

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While the nuances of the Portfolio Theory are difficult to grasp, the basic ideas are clear: diversification and risk/return optimization leads to a stronger portfolio.


Investors have used the Portfolio Theory strategy to compile an investment portfolio for years. As an investor, it is useful to diversify and to optimize investment holdings that will generate returns. The Portfolio Theory is beneficial to a company or an investor who wishes to have a deeper understanding of the risk and reward relationship. By looking closely at the amount of acceptable risk, an investor gets an idea of the type of investments they should select. Many investors consider themselves as ‘risk-takers’ but when confronted with actual data about the risk involved, prefer to take a safer, more traditional route. Other investors consider themselves as conservative but would be comfortable with a higher level of risk. Evaluating the level of risk that can be tolerated gives an understanding of an investor’s risk tolerance.

In corporate applications, the Portfolio Theory is useful to establish a strategy for increasing and optimizing a corporate portfolio. Again, it gives an indication of risk tolerance, but it also provides opportunity for discovering methods of diversifying a company’s holdings and offerings. Developing areas that can increase rewards, while balancing the risks is essential in stable companies.

Finding the perfect balance of risk versus reward is the fundamental basis for the Portfolio Strategy – making it extremely useful for the company that wishes to minimize their risk.


There are four main components in the Portfolio Theory: risk, return, efficient frontier, and diversification.


The Portfolio Theory assumes that when given a portfolio of investments with equal returns, the investor will select the one with the lower level of risk. According to the assumptions of the theory, an investor will only take on additional risk if there is an expected level of higher reward. The relationship between risk and return is affected by the number of assets in the portfolio.


With the framework of the Portfolio Theory, an investor who wants to generate a higher level of reward, or return, must be willing to have a higher level of risk. The implication, then, is that an investor will choose to invest in a portfolio that offers a lower level of risk with the highest level of return.


Markowitz’s theory demonstrates that an investor who wishes to reduce risk can do so by establishing a diverse portfolio. Using mathematical principles and formulas, the return variance of the portfolio can be established. Simply put, the sum of the assets, over the square of the fraction of assets is multiplied by the asset’s return variance. When the assets are completely uncorrelated, the portfolio is diversified and the investor can experience a higher level of reward.

Efficient Frontier

Also known as the Markowitz bullet, the Efficient Frontier is the graphical representation of the Portfolio Theory. By plotting the possible combinations of assets to risk, the risk-free area is clearly identified on a hyperbola graph. Moving along the risk-free rate line, an investor can begin to identify what level of risk is comfortable based on the expected level of return.


The basis for the Portfolio Theory is mathematical. A long, complex formula for investing is used to determine the risk/reward ratio and establish a diversified and optimized portfolio. Typical entrepreneur might not have the desire or know-how to establish a mathematical formula to determine investments in products and projects within her/his business, however, and the statistical data for the strategy is lost on many.

Creating a true Portfolio Theory strategy for a company, then, requires the assistance of financial planners and potentially fund managers who have access to tools and data streams to provide information. The concepts of the strategy, however, can be clearly understood and used by even the most novice investor or entrepreneur in her/his business.

Investors can establish their portfolio two ways. Identifying the acceptable level of risk gives an idea of the expected level of returns. Conversely, identifying the desired returns will identify the amount of risk necessary. Applying diversification will spread the risk over a number of assets, lessening the individual risk but increasing the overall return.


The Portfolio Theory has a wide range of applications outside the world of finance. Modern users of the theory have applied it to scientific processes, charting the possible outcomes of experiments. It has been used to find relationships in the workplace with studies of variability and economic growth in the labor force. Social psychology has adapted the theory to develop a model of self-concept. According to psychologists, an individual’s self-esteem is stable when their self-concept is more diverse.

The same principles can be applied in a business setting, where the fundamentals of Portfolio Theory can be applied to corporate strategy. For companies that have multiple divisions, offer a line of products or services, using the Portfolio Theory can lead to a more stable and consistent revenue stream. In addition, it can offer a company clearer vision of how to increase their market share, while minimizing risk.

A company that wishes to increase their reward (or, put another way, to generate more revenue) can institute the Portfolio Theory. Adding a diversified set of assets will lessen the risk of diminishing returns. In the oil refinery company example used above, the company selected diversity of oil fields based on their risk/return profiles. It reduced the risk on the portfolio level (by selecting lower level risk oil fields), added diversity (by selecting several oil projects), and increased revenue (by selecting higher revenues for defined level of risk). Finding ways for adding diverse projects with optimized risk / return profile can help a company grow and profit.

Finding ways to apply the Portfolio Theory to a business’ strategy will increase their stability within the marketplace. Looking at a company’s portfolio of products / projects overall will help drive decisions about adding or reducing the number of products / projects, in direct correlation to the amount of return desired. If one department or division is not performing well, it will not be as detrimental when other divisions can offset the deficit. The company can then make decisions regarding the addition of a new asset to replace the poorly performing section or to develop methods to increase that division’s revenues.


It is helpful to evaluate the corporate application of the Portfolio Theory by examining a company that uses the strategy to determine their growth. One of the largest companies around, General Electric (GE) has a long history of diversification and product portfolio optimization. Within the last few years, however, they have streamlined their corporate structure into six main areas: banking, transportation, appliances and lighting, aviation, energy and health care.


© General Electric

To apply the Portfolio Theory, consider each industry as an asset. Limiting their assets to six, they have optimized their risk/reward formula. By selecting industries that operate independently of each other, they have a range of diversification without high elements of risk. The reward component of the formula can be seen in the potential for double-digit growth in earnings for 2014. With a focus on developing within the industries they have chosen, they are increasing their organic revenue in an environment that allows for low reward in one area balanced by the higher rewards in another.

Over the last several years, the largest growth revenues have come through GE’s banking industries. The smallest revenues have been through their transportation division. Based on the Portfolio Theory, they can still achieve high levels of reward, due to the relationship between their risk factors. In an effort to further stabilize their revenues, GE has been putting their efforts into bolstering their transportation division, while pulling back from their banking industry. As the recession has receded, demand for GE’s locomotive has increased with the recovering railway industry.

By achieving industrial growth that is sustainable, GE has managed to remain a stable force in the marketplace. Examining the relationship between the different industries that GE offers, it is clear to see how the Portfolio Theory can be applied to a corporation with success. Considering the overall portfolio of GE shows a company that has a high level of revenue, with an overall low level of risk, making GE a strong investment opportunity.

The Portfolio Theory as a strategy for business can demonstrate the elements of acceptable risk and reward helping companies to diversify and to optimize their portfolio of products and services, as well as to establish a strong market presence. While critics of the theory have held that the idea is based in an unreal world of perfect conditions, the principles of the strategy have clearly worked. Variations of the Portfolio Theory have developed since its inception and it still continues to be a much-used method of investing and business planning today. By taking this investment strategy and applying it to other areas of business, the long heralded method is still as effective as it was over thirty years ago.

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