Building a Balanced Portfolio with Constraints and Limits: Practical Tips for Achieving Your Investment Objectives

Michal Dufek
4 min readMar 10, 2023

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Want to optimize your investment portfolio for maximum returns? Look no further than the power of constraints and limits. By applying these practical techniques to your portfolio, you can achieve a better balance of risk and reward and meet your investment objectives with ease. In this article, we’ll explore the real-world benefits of portfolio optimization with constraints and limits, and show you how to use these tools to build a well-diversified portfolio that delivers results.

Portfolio optimization is a powerful tool that investors use to build a portfolio of assets that maximizes returns while minimizing risk. One way to achieve this is by applying specific constraints to the portfolio, such as limiting the weight of certain assets, alternating specific companies in the portfolio, or forcing a specific number of companies in the portfolio.

Here are some specific examples of portfolio optimization use cases that demonstrate the benefits of applying these constraints:

  1. Limiting the weight of certain assets

Suppose an investor has a portfolio of tech stocks and wants to limit their exposure to a particular stock, such as Apple. The investor can use portfolio optimization techniques to set a maximum weight constraint on Apple’s stock, ensuring that it doesn’t make up too much of the portfolio. For example, let’s say the investor has $100,000 to invest in tech stocks and wants to limit their exposure to Apple to no more than 20% of the portfolio. The investor could use mean-variance optimization to determine the optimal allocation of assets that meets this constraint.

| Asset | Weight | Return | Standard Deviation |
|-------|--------|--------|-------------------|
| Apple | 20% | 10% | 20% |
| Google| 30% | 8% | 15% |
| Amazon| 30% | 12% | 25% |
| Tesla | 20% | 15% | 30% |

In this example, the investor’s optimal allocation would be to invest 20% of their portfolio in Apple, 30% in Google, 30% in Amazon, and 20% in Tesla.

2. Alternating specific companies in the portfolio

Some investors may want to build a portfolio that includes exposure to multiple companies in a particular sector or industry. However, they may also want to limit their exposure to any single company in that sector. To achieve this, investors can use portfolio optimization techniques to alternate between specific companies in the portfolio, ensuring that no single company dominates the portfolio.

For example, suppose an investor has $100,000 to invest in the healthcare sector and wants to include exposure to four companies: Pfizer, Johnson & Johnson, Merck, and Novartis. The investor wants to limit their exposure to any single company to no more than 25% of the portfolio. The investor could use mean-variance optimization to determine the optimal allocation of assets that meets this constraint.

| Asset          | Weight | Return | Standard Deviation |
|----------------|--------|--------|-------------------|
| Pfizer | 25% | 5% | 10% |
| Johnson & Johnson | 25% | 8% | 12% |
| Merck | 25% | 7% | 15% |
| Novartis | 25% | 9% | 18% |

In this example, the investor’s optimal allocation would be to invest 25% of their portfolio in Pfizer, 25% in Johnson & Johnson, 25% in Merck, and 25% in Novartis.

3. Forcing a specific number of companies in the portfolio

Another use case for portfolio optimization is to force a specific number of companies in the portfolio. For example, an investor may want to build a portfolio that includes exposure to ten different companies but wants to ensure that no single company dominates the portfolio. By using portfolio optimization techniques to set constraints on the number of companies in the portfolio, investors can achieve this goal.

For example, suppose an investor has $100,000 to invest in the energy sector and wants to include exposure to ten different companies. The investor wants to ensure that no single company makes up more than 10% of the portfolio. The investor could use mean-variance optimization to determine the optimal allocation of assets that meets these constraints.

| Asset      | Weight | Return | Standard Deviation |
|------------|--------|--------|-------------------|
| Exxon | 10% | 7% | 15% |
| Chevron | 10% | 5% | 10% |
| ConocoPhillips | 10% | 8% | 20% |
| BP | 10% | 9% | 18% |
| Royal Dutch Shell | 10% | 6% | 13% |
| Total | 10% | 7% | 12% |
| Eni | 10% | 10% | 25% |
| Gazprom | 10% | 12% | 30% |
| PetroChina | 10% | 8% | 22% |
| Sinopec | 10% | 11% | 28% |

In this example, the investor’s optimal allocation would be to invest 10% of their portfolio in each of the ten companies. This ensures that no single company dominates the portfolio and the investor has a well-diversified portfolio.

In conclusion, portfolio optimization is a powerful technique that can help investors achieve their investment goals. By applying specific constraints, such as limiting the weight of certain assets, alternating specific companies in the portfolio, or forcing a specific number of companies in the portfolio, investors can build a portfolio that is well-diversified and balanced. With the help of portfolio optimization techniques, investors can make more informed investment decisions and maximize their returns while minimizing their risk.

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