Measuring Sticks and Sleight of Hand: How Funds Choose Benchmarks Designed to Make Them Look Good

Every fund tells a story about its own performance. The benchmark it selects is the narrative device that shapes whether that story reads as a triumph or a failure. Yet most retail investors accept their fund's stated comparison index without question, treating it as an objective, neutral reference point chosen in the spirit of transparency. In reality, benchmark selection is frequently a strategic decision — one that flatters the manager far more than it serves the investor.

Understanding how this process works, and how to construct more meaningful performance comparisons, is an essential step toward making genuinely informed investment decisions.

Why Benchmark Selection Is Never Truly Neutral

Funds are not required by law to benchmark themselves against the most rigorous or most relevant index available. They must disclose a benchmark, but the choice itself is largely discretionary. This creates an obvious incentive: managers who underperform their natural peer group have strong motivation to identify a comparison index that presents their track record in a more favorable light.

The mechanics of this are straightforward. A large-cap growth fund that has struggled to keep pace with the S&P 500 Growth Index might instead benchmark itself against the broader S&P 500, which includes slower-growing value stocks that historically drag on returns during bull markets. A fund with meaningful international exposure might select a domestic-only index during periods when US equities are outperforming global markets. A bond fund holding below-investment-grade securities might compare itself against an investment-grade benchmark when credit spreads are widening and high-yield instruments are suffering.

In each case, the fund can plausibly claim it has beaten its benchmark — while simultaneously delivering results that a knowledgeable investor would recognize as mediocre or worse.

The Three Most Common Benchmark Manipulation Tactics

Selecting a broader, more diluted index. When a fund pursues a focused strategy — concentrated in technology, healthcare, or small-cap value, for instance — comparing it against a broad market index like the Russell 3000 or the total stock market allows pockets of underperformance to be obscured by sectors the fund doesn't even hold. The comparison is structurally unfair to the investor trying to evaluate whether the manager is adding value.

Cherry-picking the time frame around the benchmark. Funds occasionally switch benchmarks after periods of poor relative performance, effectively resetting the performance narrative. The new benchmark is introduced going forward, but the historical record of underperformance against the old index quietly fades from prominence in marketing materials. This practice is technically disclosed in fund documents, but the disclosure is rarely prominent.

Using a benchmark that doesn't account for dividends. Price-return indices exclude dividend reinvestment, while total-return indices include it. A fund that compares its total returns — dividends included — against a price-return benchmark is giving itself a built-in advantage that can amount to one to three percentage points annually, depending on the yield profile of the underlying holdings. This discrepancy is particularly common in funds that hold dividend-paying stocks or income-generating securities.

How to Identify a Mismatched Benchmark

The first step is to examine the fund's actual portfolio holdings and compare their characteristics against those of the stated benchmark. If a fund claims to track its performance against the S&P 500 but holds a significant allocation to mid-cap companies, international equities, or alternative assets, the mismatch is self-evident. Tools such as Morningstar's style box analysis or a fund's own portfolio disclosure filings can help surface these inconsistencies.

Second, look at the benchmark's historical volatility relative to the fund's own standard deviation. A legitimately comparable benchmark should exhibit similar volatility patterns. If the benchmark consistently shows lower drawdowns during market stress periods, it may be structurally less risky than what the fund actually holds — meaning the fund is being credited with outperformance that is simply compensation for taking on more risk.

Third, investigate the benchmark's composition for factor exposures. A fund with a strong value tilt should be benchmarked against a value index, not a blend or growth index. The same logic applies to size, geography, duration (in fixed income), and sector concentration. When factor exposures are meaningfully different between the fund and its benchmark, performance comparisons become unreliable guides to managerial skill.

Building a More Honest Performance Framework

The most useful approach for individual investors is to construct what analysts sometimes call a "custom blended benchmark" — a composite index that reflects the actual asset allocation and factor exposures of the fund in question. For example, if a fund maintains roughly 60 percent in US large-cap equities, 20 percent in international developed-market equities, and 20 percent in investment-grade bonds, a blended benchmark combining the S&P 500, the MSCI EAFE Index, and the Bloomberg US Aggregate Bond Index in those proportions would provide a far more meaningful performance reference than any single index the fund might choose to highlight.

This approach requires more effort than accepting the fund's stated benchmark, but it produces a comparison that actually reflects your investment goals rather than the manager's marketing objectives. Several portfolio analysis platforms, including those available through major brokerage accounts, offer tools to construct and track custom benchmarks over time.

Beyond benchmarks, it is worth evaluating fund performance against a simple, low-cost passive alternative that replicates a similar strategy. If an actively managed US large-cap growth fund charges 0.75 percent annually and benchmarks itself against the S&P 500, the more honest question is not whether it beat the S&P 500 — it's whether it beat a Vanguard or iShares large-cap growth ETF charging 0.04 percent. After fees, taxes, and transaction costs, the hurdle for active management is considerably higher than a raw benchmark comparison suggests.

What This Means for Portfolio Decision-Making

Benchmark manipulation doesn't just distort how a single fund appears — it distorts portfolio construction decisions over time. Investors who believe their funds are genuinely outperforming relevant benchmarks may allocate more capital to those funds, accept higher fees as justified, and hold positions longer than is warranted. The cumulative cost of those decisions, compounded over years, can be substantial.

At InvestFunds, our view is that rigorous fund evaluation begins with skepticism toward the performance narratives that fund companies construct. The benchmark a fund chooses tells you something important about the manager's priorities. When that choice appears designed to flatter rather than inform, treat it as a signal — not just about past performance, but about the fund company's broader relationship with transparency.

The right benchmark for your purposes is not the one printed in the fund's fact sheet. It is the one that honestly reflects what you are trying to achieve, what risks you are accepting, and what alternatives you are forgoing. Building that framework takes work, but it is the foundation on which sound investment decisions are made.