Benchmarks Are Broken: Why Antiquated Methodologies Fail Fixed Income

by Ben Hernandez of VettaFi, 6/24/26

The early 1970s made for interesting times. Political turbulence amid the Vietnam War, cultural rebellion, and escapist entertainment were rampant. 1973, in particular, saw the creation of the first total-return bond indexes that tracked U.S. government and U.S. investment-grade corporate bonds. These early fixed income indexes weighted bonds by the outstanding debt vis-a-vis a market cap-weighted approach, which has persisted over the years. Fast forward just over a half a century later, the financial industry is still operating under a monolithic assumption that the best way to track a market is by weighting its constituents according to market capitalization. It’s time for a change.

While the market-cap methodology has been the guiding principle for equity index creators, it’s increasingly viewed as a structural error in the world of fixed income. Today, TMX VettaFi is helping to spearhead a growing movement of index innovators who are inclined to challenge the fixed income status quo. A conversation with Samarth Sanghavi, head of fixed income index product, further underscored this notion that traditional bond benchmarks are fundamentally misaligned with the needs of today’s investors.

Key Takeaways:

Traditional fixed income benchmarks rely on market-cap weighting, which effectively rewards the most indebted companies with the highest index allocations regardless of their credit quality.
Unlike equities where size reflects value, bond investors win by not losing; prioritizing high-debt issuers indiscriminately increases exposure to default risk in a high-interest-rate environment.
Firms like TMX VettaFi are reengineering the fixed income status quo by shifting toward equal-weight and smart beta indices that emphasize fundamental credit quality over sheer debt volume.

See More: VettaFi’s Sanghavi Talks Fixed Income Opportunities and More

The Debt-Weighting Fallacy

One of the core issues with today’s fixed income index methodologies is within the mathematical logic of traditional benchmarks. In equities, a company’s market cap generally aligns its value and relative market sentiment. Financial academia knows this as an efficient market. But in fixed income, market-cap weighting is synonymous with debt-weighting. Essentially, the issuers with the largest outstanding debt automatically get the highest representation in the benchmark. Sanghavi characterized this approach as a fundamental disconnect.

“Debt weighting is not an investment thesis,” Sanghavi noted. “What we’re saying is there are 10 companies here and the company who has the most debt receives the highest exposure. That’s not quite right in my mind.”

By rewarding the most indebted issuers with the highest allocation in an index, traditional benchmarks overlook an important factor of analysis: debt quality. Simply, the sheer volume of issuance becomes the ultimate determining factor, rather than the likelihood of a company meeting its debt obligations. For investors seeking to preserve their capital by mitigating credit risk, this creates a counterintuitive reality. It gives the portfolio inherent bias toward companies borrowing the most rather than those with fortified balance sheets.

The Philosophy of Capital Preservation

On the topic of capital preservation, this is where current indexing methodologies based on market capitalization also falter. In fixed income, capital preservation typically takes precedence over aggressive growth. In the bond market, the asymmetry of outcomes is stark. A successful investment returns the principal and the coupon, while a failed investment can ultimately lead to a total loss of principal. This is where Sanghavi sees the need for adopting a different mindset.

“In fixed income, you win by not losing,” Sanghavi said, echoing the words of Brian Coco, TMX VettaFi’s head of index products. Because bond investors cannot capture “double coupons” if a company performs exceptionally well, the primary mandate is to avoid a default.

By prioritizing high-debt issuers indiscriminately, traditional benchmarks of yesteryear may inadvertently increase an investor’s exposure to companies that are most likely to face liquidity constraints or default scenarios. This is especially pertinent in the current macroeconomic environment, where higher-for-longer interest rates are keeping debt servicing costs elevated. This presents an opportunity for index reengineering.

Reengineering Fixed Income Indexes

As Sanghavi explained, one of the avenues to lead fixed income forward is a transition into smart beta and equal-issue-weighted indices. By reengineering how these benchmarks are constructed, firms like TMX VettaFi seek to create products that outperform flawed traditional benchmarks. This involves moving away from the “market cap by default” approach into strategies that emphasize fundamental quality and structural resilience.

“Benchmarks are broken,” Sanghavi asserted. That signals a broader shift toward indexing as more than an ancillary research product. Rather, it can be a tool for generating real, differentiated value.

In an increasingly complex market, it’s imperative to look “under the hood” of indices to avoid exposure to debt-heavy benchmarks. The era of blindly following debt-weighted indices is becoming supplanted by indices that reflect actual credit quality.

See More: The Bond Index Isn’t Dead — It’s Just Getting Smarter

The Solution for Broken Benchmarks

The established premise — that typical fixed income indexing methodologies are in need of fixing — leads to an obvious question. How does it get fixed?

In a separate story, we’ll delve into innovations from TMX VettaFi. Those include sophisticated technology allowing issuers to filter indices by sector, duration, and rating to build more precise, customized exposures. By continuously innovating within the fixed income index space, VettaFi is turning antiquated benchmarks into relics of the past — empowering issuers and investors to regain structural control over their portfolios.

Originally published on ETF Trends

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