Modern Portfolio Theory

In this lesson, you’re expected to learn about:
– portfolio management strategies
– the efficient market hypothesis
– diversification

What is an investment portfolio?

An investment portfolio isn’t a physical thing or single entity. It is a collection of different investments treated as a single combination.

You can measure and analyze an investment portfolio as a single collection of different investments and do the same for each individual investment within a portfolio.

Portfolio Management

Portfolio management is the buying, selling and trading of investments within a portfolio – optimizing the returns of the portfolio by managing which investments the portfolio holds.

But the portfolio itself remains constant despite the changes of its exact contents. The portfolio changes only when the underlying investment strategy changes.

For this reason, organizations often have many investment portfolios. Each portfolio is managed using a unique strategy based on the goals of the investors.

For example, a company may have a stock investment portfolio that it uses to generate returns on petty cash, while also maintaining a capital investment portfolio that includes land, corporate acquisitions and subsidiaries and other types of capital.

Each of these portfolios has different contents and different purposes for existing, and the strategies involved in managing the contents are different as well.

Portfolio Management Strategies

1) Debt Portfolio 

This type of investment portfolio invests exclusively in bonds of different types and with different maturity dates, usually with the intention of staggering maturity dates and coupon maturities in order to maintain regular cash flows.

2) Hedge Portfolio 

It is intended to hedge other forms of risk by managing derivatives and diversifying investments. A portfolio like this changes based on the types or amount of risk the company is accepting.

3) Slush Fund / Petty Cash Portfolio 

A company that maintains a cash account for irregular small payments that crop up from time to time can still generate a return on this cash by maintaining a portfolio of short-term, highly liquid investments.

Note: Throughout this lesson, we refer to stock investment portfolios but we’ll use the term ‘stock’ for the sake of consistency. You can include any type of investment – whether shares, bonds, capital or options – in an investment portfolio and analyze them using different methods.

Modern Portfolio Theory 

Modern portfolio theory isn’t about how to value individual investments but instead how to assess the potential combinations between several investments. The relationship between two or more assets can change the balance of a portfolio’s total returns and the total risk involved.

Modern portfolio theory uses a number of mathematical formulae and modeling in an attempt to formalize a method of improving your understanding of investing.

[Optional] What is Modern Portfolio Theory?
Check out this 3-minute video to learn more:
Passive vs. Active Management

1) Passive portfolio management 
Refers to setting up a portfolio to match the entire stock market or some well-known index as closely as possible. When established, these portfolios are simply left alone to fluctuate along with the indicator that the portfolio is set up to follow.

2) Active portfolio management 
Involves regularly changing the contents of a portfolio. Every portfolio manger has his own strategies and methods for analyzing and optimizing returns but the point is that the portfolio manager is buying, selling and trading the underlying investments actively. He may try to take advantage of short-term fluctuations in price by making multiple trades every day.

Regardless of the approach you take, actively managing a portfolio is a full-time job. It entails constantly re-evaluating existing investments, searching for new investments and assessing the degree of risk and the returns being generated by the portfolio as a whole.
[Optional] Portfolio Management Strategies
Efficient Market Hypothesis

The efficient market hypothesis states (incorrectly) that the market responds instantly to new information, ensuring that all investments and assets are valued at their fair market price.

According to the hypothesis, if people all have the same information at the same time and have equal access to exchange markets, prices adjust instantly to their economic equilibrium.

If the efficient market hypothesis were true, any opportunities to generate returns on investments are useless because all investments instantly change to their proper price whenever new information becomes available.

After all, not everyone has the same information; some people know more than others and many receive information at different times and process it in different ways. In addition, people don’t have equal access to exchanges.

The decisions that people make regarding investments vary as well because investors react to news in different ways, have different strategies and measure the value of stocks differently.

The market is efficient only in the long term. In the short term, frequent and intense levels of volatility can push the value of an asset, investment or even an entire company well away from its real value.

[Optional] The Efficient Market Hypothesis and Its Shortcomings
Risking Returns

Risk is an unavoidable part of corporate finance. If a company were to try to eliminate financial risk, all operations within the entire organization would come to a standstill.

Instead of trying to avoid risk, companies tend to make choices that have the biggest differential between risk and financial returns. They measure the amount of returns they expect on a potential investment and determine the potential costs associated with the risks of that investment. Then they use mathematical modeling to determine their best investment option.

In portfolio management, you can minimize the level of total risk and still maximize financial returns by carefully measuring how different investments change in value compared to each other in multi-asset interactions.
Trade-off between Risk and Return 

A central tenet of modern portfolio theory is that a trade-off exists between risk and return. All things being equal, if a particular investment incurs a higher risk of financial loss for prospective investors, those investors must be able to expect a higher return in order to be attracted to the higher risk.

Just because an investor believes that a higher risk investment is going to generate higher returns doesn’t necessarily make it true. Sometimes higher-risk investments become less risky over time, attracting more investors who then drive up the price/value of the investment by competitively outbidding each other.

Whether or not a riskier investment does generate higher returns is up to the individual investor to decide. 

– how risk is assessed and the amount or expected returns, changes depending on the individual investor.

– investors will invest in higher-risk opportunities if they feel that doing so is going to generate higher returns.

Diversifying to Maximize Returns and Minimize Risk

The risk of a single investment can’t be completely eliminated so companies attempt to reduce the risk of a portfolio by picking investments that are likely to change in value in different ways or at different times. This process is known as diversification.

It means taking advantage of differences in risk among your investments and the fact that investments tend to change in value at different times and even in different directions. So if your portfolio consists of several different investments and only one of them loses value, the portfolio loses a smaller percentage of its value than a single investment does.

Goal of Diversification 

To reduce risk by finding several investments that change in value at different times, in response to different events, by different percentages or in completely different directions.

In this way, you reduce the severity of any losses that may occur in a portfolio from the risk associated with only one investment. You can measure the effectiveness of portfolio diversification mathematically which we will cover later.

So why don’t companies just invest all their money in only the best assets instead of diversifying? 

Warren Buffet, CEO of Berkshire Hathaway Inc., claims that diversification is used only when a company lacks confidence or ability, maintaining that diversification is a tool only for the incompetent. Thus, diversification simply for the sake of diversification isn’t very helpful. The point of diversification is to reduce the risk to your portfolio more than you reduce the returns.

Let’s look at an example.

Say that Investment A generates 10% annual returns, Investment B generates 5% annual returns and your portfolio has an equal split between Investments A and B. X is the amount of portfolio risk as a percentage of total value. In this example, 7.5% is the amount of annual returns generated by the portfolio.

Thus, you want to look for the best investments you can find and then diversify by purchasing those investments that provide the highest returns but risk losing value under directly opposite conditions.

[Optional] How Much Diversification is too Much or Little?
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