Rethinking Traditional Portfolio Theories

In the ever-evolving landscape of financial markets, the question of whether traditional Modern Portfolio Theory (MPT) investing rules still hold up has become increasingly relevant. As we navigate through today's dynamic environment, it is crucial to reassess and adapt our investment strategies to align with the changing landscape.

The Foundation of Modern Portfolio Theory

Modern Portfolio Theory (MPT), developed by Harry Markowitz in the 1950s, has long been a cornerstone of investment strategy. The core tenet of MPT is diversification – the idea that spreading investments across different asset classes can optimize returns for a given level of risk. The traditional approach involves constructing a well-balanced portfolio of stocks and bonds based on historical return and risk data.

The investment landscape has undergone a significant transformation since the inception of MPT. Here are some key factors to be mindful of as you build an asset allocation:

1. Low Interest Rates

In today's environment of persistently low interest rates, the traditional 60/40 portfolio (60% stocks and 40% bonds) may not provide the same level of diversification benefits. With interest rates near historic lows, the bond component may not offer the same yield and risk mitigation as in the past.

2. Technological Disruption

The rapid pace of technological innovation has introduced new sectors and asset classes that were not prevalent when MPT was formulated. Investments in technology, cryptocurrencies, and other emerging industries may not conform to the historical data that MPT relies on.

3. Globalization and Geopolitical Risks

Increased interconnectedness of global markets and geopolitical uncertainties add a layer of complexity to traditional portfolio construction. Events in one part of the world can now have far-reaching effects on an array of asset classes.

4. Use of Derivatives and Fintech

Placing trades and making bets for or against the market (derivatives) can now be done in milliseconds. These trading dynamics have added an element of volatility to market behavior.

5. Index Lacks diversification

Buying index-based investments has provided investors with a low-cost way to capture a large number of companies. While this style of investing has given more individuals access to the markets it is worth observing that the index at times lacks diversification. An example of this is the current make-up of the S&P 500: 29% of the index is concentrated in 10 companies.

Harry’s ideas about spreading risk still hold true today. The confluence of changing externalities and investment products means staying more active in portfolio decisions and understanding risks.