Why Municipalities and Residents are Paying a "Fragility Tax”

06-01-2026

Roads, bridges, city water and sewage systems are aging across the U.S., and some communities are growing fast, compelling local governments to issue bonds to fund expensive infrastructure. Municipal bonds, or “muni” bonds, allow communities to spread repayment over 10-30 years so that current and future users share the costs while keeping operating budgets stable. Investors in muni bonds are providing capital that fills a civic need. For decades such bonds have been reliable and stable sources of income for both municipalities and investors. But that has changed as more municipal debt is held through open-end mutual funds.

“Two municipal bonds from the same school district, with the same credit rating and the same maturity, can trade at very different prices. The reason is not anything about the bonds. It is who happens to own them,” says Huseyin Gulen, professor of finance and head of the Finance Department at the Daniels School.

Open-end municipal bond funds give investors easy daily access to an asset class that does not actually trade daily. But the open-endedness is quietly raising the cost of capital for cities, counties and school districts across the country through what Gulen and his coauthor Viet‑Dung Doan call the “Fragility Tax.”

In their paper, “The Fragility Tax: How Mutual Fund Ownership Links Segmented Markets,” Gulen and Doan study more than 18 million municipal bond trades between 2007 and 2021, focusing on who holds a bond, not just on the bond’s own credit quality. They find that two bonds from the same issuer, with the same rating and maturity, may trade at very different yields solely because of the mutual funds that own them.

Bonds held by mutual funds tend to be redeemed when stocks fall and jumpy investors are in a “dash for cash.” These bonds also trade at yield spreads roughly 14-25 basis points higher than otherwise similar bonds held by “stickier” funds — a gap comparable to a multi-notch credit downgrade, says Gulen.

Aggregated across the market, this Fragility Tax increases municipal borrowing costs by an estimated 1.2–2.5 billion dollars per year and is associated with roughly $34 less in bond issuance per capita (roughly $4 billion in forgone issuance annually) in more exposed counties, meaning fewer projects ever get financed.

The wedge shows up even in calm markets because sophisticated buyers price in the risk of future redemption‑driven “dash for cash” episodes; in stress periods it can widen to about 35 basis points.

The mechanism runs through investor behavior rather than issuer fundamentals. When equity markets drop, stock losses are far larger and more salient than the modest declines in muni fund shares. A well-documented cognitive bias called the “disposition effect” makes households reluctant to lock in those bigger stock losses, so they prefer to sell their muni fund shares instead. Because selling a mutual fund is one click while selling individual bonds is slow and costly, open‑end muni funds become the easiest source of cash. When redemptions spike, fund managers must sell illiquid bonds into thin markets at discounts. Markets anticipate this behavior, and that anticipation itself becomes a persistent surcharge on affected issuers.

What municipal leaders should take away

Be aware that your borrowing cost depends on who owns your debt today — not just on your rating and disclosure.

A $200 million, 20‑year general obligation issue priced at 14 basis points wider because of fragile ownership translates into roughly $3 million in extra interest over the life of the bond.

Gulen suggests some practical steps for issuers:

• Ask underwriters for a buyer breakdown at issuance and periodic holder reports so you can monitor how much of your debt sits in high‑beta open‑end funds.
• Avoid letting a single high‑beta mutual fund take an outsized share of a deal. Diversify toward more stable holders such as insurance companies, bank portfolios and separately managed accounts.
• Where feasible, cultivate local retail programs and direct retail options. Households buying directly for community reasons tend to hold bonds to maturity, reducing your exposure to fund‑driven fire sales.

Policy levers to reduce the Fragility Tax

When one investor redeems from a fund, the costs of forced sales ultimately hit taxpayers. Gulen highlights two main policy tools that could meaningfully shrink this hidden surcharge:

• Stronger, fragility‑sensitive liquidity requirements. Existing SEC Rule 22e‑4 already requires funds to classify assets by liquidity and maintain minimum liquid holdings. Tightening these requirements specifically for funds with fragile investor bases would be a targeted way to reduce the tax.
• Swing pricing and related anti‑dilution tools. If funds routinely adjusted redemption prices downward during large outflows so redeeming investors bore more of the trading costs they imposed, the first-mover advantage fueling runs would diminish and fewer bonds would need to be dumped at fire sale prices.

What investors should realize — and why selling is often unwise

Buying muni bonds is one of the most direct ways households finance their own schools, water systems, transit and other public goods.

Because holding muni bonds is a civic act, investors should:

Avoid redeeming during a panic if you have a long horizon. The Fragility Tax is largest precisely when communities can least afford it, so refusing to join a dash for cash during downturns is itself a public good.

Choose funds with thicker cash cushions, more stable investor bases and, where available, swing pricing. These design features meaningfully reduce how much your fund contributes to the Fragility Tax.

When your wealth and circumstances allow, consider holding individual bonds — via a ladder or separately managed account — so you no longer contribute to the open‑end fund fragility channel at all.