Should I always compare to the S&P 500?

## Should You Always Compare to the S&P 500?

Did your portfolio beat the S&P 500 last year? Before you celebrate or despair, let's ask a better question: *should it have?*

The S&P 500 is the default benchmark for many investors. But using it as the sole measuring stick for your unique portfolio can be like judging a fish by its ability to climb a tree. It often gives you a distorted picture of your actual performance.

## Understanding the S&P 500 and Its Limitations

The S&P 500 tracks 500 of the largest U.S. companies, covering about 80% of the American stock market's value. It’s a great indicator for large-cap U.S. stocks, but that’s where its utility ends.

### Composition Mismatch

Think about it: there are over 6,000 stocks in the U.S. market alone. The S&P 500 covers just 500 of them.

If your [diversified portfolio](/blog/what-is-diversification) holds international stocks, bonds, or real estate, comparing it to a U.S.-only, large-stock index doesn't make much sense. Imagine your portfolio is 50% U.S. stocks (mirroring the S&P 500), 30% international stocks, and 20% bonds. If the S&P 500 returns 15% in a year, but your overall portfolio only returns 10%, it doesn't automatically mean you're underperforming. The international stocks and bonds might have had lower returns, dragging down the overall number.

### Sector Concentration

The S&P 500 is often top-heavy with just a few sectors. Technology, for example, frequently dominates the index thanks to giants like Apple, Microsoft, and NVIDIA. As of late 2023, technology stocks can represent over 25% of the S&P 500's weighting.

If your portfolio is weighted differently—say, with a focus on healthcare or energy—a tech-driven S&P 500 rally might make your solid returns look weak by comparison. For example, if the S&P 500 is up 20% due to a tech boom, but your healthcare-heavy portfolio is only up 8%, it doesn't mean your healthcare investments are failing. It simply reflects the different performance of those sectors.

### Size Bias

This index is all about the big players. It completely ignores the performance of small and mid-sized companies. If you've invested in [promising small-cap stocks](/blog/guide-to-small-cap-investing), the S&P 500 tells you nothing about how that part of your strategy is working. Small-cap stocks, as measured by the Russell 2000, can sometimes significantly outperform or underperform the S&P 500 in a given year. This difference can be as large as 10-15 percentage points, highlighting the importance of using the right benchmark.

## Choosing the Right Benchmarks

So, what’s the alternative? Use a "blended benchmark" that mirrors your own [asset allocation](/blog/asset-allocation-basics).

Match each part of your portfolio to its own relevant index. This gives you a much clearer view of what's working and what isn't.

- **U.S. Large-Cap Stocks:** The S&P 500 is perfect for this slice.
- **International Stocks:** Use a global index like the MSCI All Country World Index. This index covers both developed and emerging markets, giving you a broad view of international equity performance.
- **Bonds:** Compare against the Bloomberg U.S. Aggregate Bond Index. This index represents the performance of the U.S. investment-grade bond market.
- **Small/Mid-Cap Stocks:** Use indices like the Russell 2000 for small caps or the S&P MidCap 400.

### Example of a Diversified Portfolio Comparison

Let's say you have a portfolio with the following asset allocation:

*   40% U.S. Large-Cap Stocks
*   20% International Stocks
*   30% Bonds
*   10% Small-Cap Stocks

Here's how you would create a blended benchmark:

| Asset Class          | Allocation | Benchmark                               |
|----------------------|------------|-----------------------------------------|
| U.S. Large-Cap Stocks| 40%        | S&P 500                                 |
| International Stocks | 20%        | MSCI All Country World Index            |
| Bonds                | 30%        | Bloomberg U.S. Aggregate Index          |
| Small-Cap Stocks     | 10%        | Russell 2000                            |

To calculate your blended benchmark's return, multiply each benchmark's return by its corresponding allocation percentage and then sum the results. For example, if the S&P 500 returned 12%, the MSCI All Country World Index returned 8%, the Bloomberg U.S. Aggregate Index returned 3%, and the Russell 2000 returned 15%, your blended benchmark return would be:

(0.40 * 12%) + (0.20 * 8%) + (0.30 * 3%) + (0.10 * 15%) = 4.8% + 1.6% + 0.9% + 1.5% = 8.8%

Now you can compare your portfolio's actual return to this 8.8% blended benchmark to get a more accurate assessment of your performance.

## Real-World Performance Differences

Drilling down into benchmarks reveals interesting truths. It’s not just about your portfolio versus the index, but also how individual stocks perform within it.

[Research from S&P Dow Jones Indices](https://www.spglobal.com/spdji/en/research-insights/articles/the-sp-500-is-not-the-market/) has shown that over various periods, the average S&P 500 stock has actually beaten the index itself by 1.41% to 4.80% annually. This happens because the index's performance is dragged down by its worst performers, reminding us that a simple average can hide a lot of detail. This highlights the impact of weighting methodologies within the index and the potential for active stock picking to add value.

For instance, imagine a scenario where 490 stocks in the S&P 500 increase by 5%, but 10 stocks decrease by 50%. The overall index performance would be significantly lower than the average performance of the individual stocks.

## Common Mistakes and Considerations

### Mistake: Over-Reliance on a Single Benchmark

Using only the S&P 500 gives you an incomplete story. The goal of a [diversified retirement portfolio](/blog/planning-for-retirement) isn't just to beat one index; it's to grow wealth steadily across different market conditions. Many investors fall into the trap of chasing S&P 500 returns, potentially neglecting other asset classes that could provide diversification and stability. This can lead to a portfolio that is overly concentrated in U.S. large-cap stocks and vulnerable to market downturns.

### Consideration: Asset Class Volatility

It’s easy to get distracted by what’s hot. One year, tech is soaring; the next, it could be energy. In 2020, technology stocks significantly outperformed other sectors due to the pandemic-driven shift to remote work and online services. However, in 2022, with rising interest rates and inflation, energy stocks outperformed as demand surged and supply remained constrained.

Resist the urge to chase last year's winners. A well-diversified strategy is designed to smooth out those peaks and valleys over the long run. Rebalancing your portfolio regularly helps maintain your desired asset allocation and prevents you from becoming overly exposed to any one asset class. For example, if your target allocation is 60% stocks and 40% bonds, and your stock allocation grows to 70% due to market gains, you should sell some stocks and buy bonds to bring your portfolio back to its original allocation.

### Mistake: Ignoring Risk-Adjusted Returns

It's not just about how much you earn, but also how much risk you take to earn it. A portfolio that generates high returns but experiences significant volatility might not be suitable for a risk-averse investor. Consider using metrics like the Sharpe Ratio, which measures risk-adjusted return, to compare your portfolio's performance to its benchmark. A higher Sharpe Ratio indicates better risk-adjusted performance.

### Consideration: Tax Implications

Constantly chasing benchmarks and rebalancing your portfolio can trigger capital gains taxes, which can eat into your returns. Be mindful of the tax implications of your investment decisions and consider strategies like tax-loss harvesting to minimize your tax burden.

## Actionable Tips for Better Benchmarking

1.  **Determine Your Asset Allocation:** Clearly define your target asset allocation based on your risk tolerance, investment goals, and time horizon.
2.  **Select Appropriate Benchmarks:** Choose benchmarks that accurately represent each asset class in your portfolio.
3.  **Calculate Your Blended Benchmark:** Calculate the weighted average return of your chosen benchmarks based on your asset allocation.
4.  **Track Your Performance Regularly:** Monitor your portfolio's performance against your blended benchmark on a regular basis (e.g., quarterly or annually).
5.  **Rebalance Your Portfolio:** Rebalance your portfolio periodically to maintain your desired asset allocation and ensure that your risk profile remains aligned with your investment goals.
6.  **Review and Adjust:** Review your asset allocation and benchmarking strategy periodically to ensure that they still align with your changing circumstances and investment goals.

## Key Takeaways

*   The S&P 500 is a useful benchmark for U.S. large-cap stocks, but it's not appropriate for evaluating a diversified portfolio.
*   Using a blended benchmark that reflects your asset allocation provides a more accurate assessment of your portfolio's performance.
*   Consider risk-adjusted returns and tax implications when making investment decisions.
*   Regularly review and adjust your asset allocation and benchmarking strategy to ensure that they align with your changing circumstances and investment goals.

## Bottom Line

Measuring your portfolio against the S&P 500 alone is a flawed approach. It’s like using a bathroom scale to measure your height—you’re using the wrong tool for the job.

Instead, build a custom benchmark that reflects your specific investments. This will give you honest feedback on your strategy and help you make smarter decisions for your financial future.