How SMAs and ETFs can Shape a Client’s Muni Profile

Municipal bond investing is often reduced to a neat little headline: federal income tax-free along with relative stability. But this doesn’t tell the whole story. There can be many nuances to municipal bond investing, and advisors know that this is only the front door of a newly constructed house. The real work starts after you walk inside, when the question shifts from “Does this make sense?” to “What exactly are we trying to build here?”

In practice, the first step should be defining the finished product: how steady tax-exempt cash flow should be, how useful realized losses may be over time, how much state specificity matters, and how much customization the client actually needs. A municipal bond allocation held through an actively managed SMA may do one job exceptionally well; an ETF sleeve may do another. Both can be valuable, but they are not interchangeable, and the after-tax result can look very different depending on what tool is doing which job.

That framing is essential. Many muni conversations start by arguing over the materials before anyone has looked at the blueprint for the project.

What role should municipal bonds play in a client’s portfolio?

In municipal portfolios, active SMAs and ETFs are not competing products so much as different contractors on the same job site. The SMA is the custom builder. It works one bond at a time, one tax lot at a time, one household at a time. The ETF is the modular builder. It arrives with certain diversification¹, liquidity, and scale already built in, which is exactly what many advisors need when managing model portfolios or making changes across multiple accounts.

That distinction matters because good construction starts with the plan, not the tools. Some clients need a custom home. Others need a well-built addition that can be installed quickly and cleanly. Quite a few need both. The mistake is assuming every muni allocation should be built the same way, as if every client walked into the office asking for identical floor plans.

A more effective advisor to client conversation begins with the blueprint: How should this part of the portfolio behave? Should it prioritize stable tax-exempt income? Should it preserve flexibility to realize losses against gains elsewhere? Should it be easy to scale inside a broader model? Those are not wrapper questions. They are design questions. And no good architect starts with leftover lumber and calls it a plan.

How can SMAs support customized muni portfolios?

For many high-net-worth households, the active SMA is the precision tool. Direct ownership of individual bonds allows advisors and portfolio managers to define credit exposure one CUSIP at a time, set state and sector limits, and choose structures that align with a client’s goals and risk tolerance. In today’s market, that often means owning premium-priced bonds with higher coupons. That may not sound flashy, but neither does a solid foundation. Both tend to matter more when the weather changes.

That is especially true in a market where only about 1-2% of outstanding municipal securities trade on a typical day, according to the MSRB (Aleis Stokes, 2024). This is not a hardware store where every part is sitting neatly on the shelf. It is a trade-by-appointment market, which makes security selection, portfolio construction, and execution discipline far more important than they might appear from a simple tax-equivalent yield screen.

The potential tax profiles of an SMA also deserve more attention. In separately managed accounts, for example, premium on tax-exempt bonds is amortized over time, reducing basis in a way that generally keeps the tax outcome closer to the bond’s underlying economics if held to call or maturity. In plain English, the SMA is not just where advisors can pick individual bonds carefully. It is also where they can help tailor the tax profile with a finer set of instruments. When losses are worth harvesting, managers may seek to sell specific bonds, realize actual economic losses to help offset gains elsewhere, and reinvest in substantially different positions while keeping the portfolio’s overall role intact. Measure twice, cut once.

How can ETFs support scalable muni portfolios?

ETFs may offer a different reward compared to investing in individual bonds. They can generally provide diversified municipal exposure that can be implemented quickly, resized efficiently, and used easily inside model portfolios. They are also typically implemented in a tax-aware manner that may result in comparatively less capital gain recognition. In builder terms, the ETF can often be the prefabricated component that shows up on schedule, fits where it should, and saves everyone from turning a straightforward remodel into a six-month custom kitchen project.

And modular construction is no longer a niche concept. Over the past three years, ETFs have captured roughly 64% of net flows into municipal strategies (Morningstar, March 2026), with mutual funds gathering the rest. In other words, the modular builder is no longer waiting in the parking lot. It is already on the job site.

But convenience is only part of the ETF story. Because of how premium amortization, distributions, and investor-level basis can interact in pooled vehicles, investors may receive tax-exempt income over time and potentially realize capital losses when ETF shares are sold after a market decline. Depending on a taxpayer’s individual circumstances, those losses might then be used to offset gains elsewhere in the household portfolio. Different jobs, different tools. The SMA gives precision at the bond level. The ETF can offer flexibility at the vehicle level.

Combine SMAs and ETFs to support (whole) portfolio planning

This is where the blueprint comes back into focus. The strongest municipal bonds portfolios are often not built by choosing between SMAs and ETFs, but by assigning each one the right job. The SMA can serve as the structural core: high-grade, customized, and designed around the client’s long-term credit, state, and tax preferences. The ETF sleeve can sit around that core as a modular piece, providing scalable exposure and daily liquidity while giving advisors a cleaner way to make credit or duration tilts, harvest diversified losses, or rebalance without disturbing the custom work underneath.

That portfolio flexibility may become especially useful at year-end. Some years, the better move may be to do the tax work inside the SMA by selectively rebalancing the portfolio, potentially harvesting losses on individual bonds and upgrading into stronger structures. In other years, it may be more efficient to make potential changes at the ETF level while letting the SMA remain intact as the long-term anchor. That is a more nuanced conversation than simply looking at muni bonds as a broad category. It turns the year-end review into what it should be: a check on the blueprint, not a scramble around the job site.

Municipal investing should not be framed as a line-item tax benefit or wrapper debate; it should be framed as a design exercise. The blueprint defines the goal, and the builders do their intended job. At BlackRock, advisors can help draw that blueprint across the full municipal platform, from actively managed SMAs with dedicated portfolio managers, to iShares ETFs built for scale supported by regional Market Leaders. And a growing body of research on municipal tax-loss harvesting and tax-optimized muni portfolios (Kalotay, “Optimal Tax-Loss Harvesting of Municipal Bonds” (CDAR, UC Berkley)) makes the case that systemic, year-round tax management may help enhance after-tax results in comparison to a simple buy-and-hold portfolio. This is exactly the kind of work this platform is built to support. Learn more about some of our muni ETFs including HIMU, MUB and INMU or our fixed income SMA platform.