The Disadvantages of Index Funds: Low Fees Don't Always Mean Low Costs
INVESTING“Price is what you pay. Value is what you get.”
— Warren Buffett
Index funds have become one of the most popular ways to invest, and for good reason. They offer diversification, simplicity, and generally very low index fund fees. But there's an important distinction investors often overlook: Low fees don't necessarily mean low costs.
The Hidden Cost of Following the Crowd
Most index funds follow a predetermined set of rules that dictate which stocks they own and when they buy or sell them.
Annually, indexes undergo a process called reconstitution, where companies are added or removed based on criteria such as size, valuation, or profitability.
Here's the catch: These changes are often announced well in advance, giving other market participants an opportunity to trade ahead of index funds.
Imagine playing poker while everyone at the table can see your cards. That's essentially what happens when an index fund announces exactly what it needs to buy or sell.
And when billions of dollars follow the same instructions, those predictable index rebalancing trades can become expensive. It's one of the quieter disadvantages of index funds, and it has nothing to do with the fee.
Not All Index Funds Are Created Equal
Investors often assume that two funds labeled "large-cap value" should perform similarly. Not necessarily.
Through August 2026, the Russell 1000 Value Index returned 23.1%, while the S&P 500 Value Index returned just 12.5%.
That's a difference of more than 10 percentage points between two indexes supposedly representing the same investment category.
The lesson? What's inside an investment matters far more than what's written on the label.
A More Thoughtful Approach
At Buttonwood Wealth, we believe successful investing requires more than simply following an index. The choice is often framed as active vs. passive investing, but it’s not that simple.
Markets change every day. Investment strategies should have the flexibility to respond thoughtfully rather than being forced to trade on an arbitrary date.
That doesn't mean predicting which stocks will outperform tomorrow. It means maintaining broad diversification, controlling trading costs, and following a disciplined, research-driven investment process.
Index funds helped revolutionize investing by making diversification affordable and accessible. But innovation doesn't stop there.
Sometimes the smartest investment strategy isn't about paying the lowest fee. It's about understanding the total cost of investing and having a process designed to deliver better outcomes over time.
The Russell 1000 Value and S&P 500 Value indexes are referenced for illustrative purposes only, to demonstrate how indexes with similar investment objectives can produce significantly different returns. This comparison is not intended as investment advice or a recommendation of either index.
Source: Dimensional Fund Advisors, The Informed Investor podcast transcript. Index returns cited are as stated in the transcript and should be independently verified before publication.