MMSD vs SUB

MMSDCNYLI MacKay Muni Short Duration ETF

SUBAiShares Short-Term National Muni Bond ETF

In short

MMSD New York Life's muni desk in ETF form, aimed at the short end of the tax-exempt bond market. It undercuts the typical muni ETF on fee, but it opened in 2025 and is still building its record.

SUB Munis, but only the near end of the curve. Since 2008 SUB has tracked an AMT-free index of investment-grade municipal bonds maturing inside five years, paying tax-exempt income monthly with far less rate sensitivity than long-dated muni funds.

Stated mandate

MMSD The Fund seeks current income that is exempt from regular federal income tax.

SUB The fund seeks to track an index of short-term, investment-grade U.S. municipal bonds maturing from one month through five years, providing tax-exempt income while managing interest-rate risk.

Why people hold it

• MMSD Costs 0.25% a year against a 0.30% median for muni bond ETFs. On tax-free income, the fee you skip is income you keep.
• The mandate targets current income exempt from regular federal income tax, and the fund distributes monthly.
• Short duration by design. Shorter bonds move less when rates jump, which is the whole point of the sleeve.
• Holds roughly 150 municipal bonds, so no single issuer carries the portfolio.

• SUB Charges 0.07% a year against a category median near 0.30%. On tax-exempt bond income, that fee gap is a meaningful slice of what actually reaches you.
• Two dials set on purpose: maturities from one month to five years, and an AMT-free index, so neither rate swings nor the alternative minimum tax hit the same way.ishares.com
• A multi-billion-dollar fund running since 2008 under iShares, with tight tracking of its ICE benchmark. One of the sturdier implementations in the muni group.
• Pays monthly, so the tax-exempt income arrives on a regular cadence rather than in quarterly lumps.

Worth knowing

• MMSD Thinly traded. Spreads can be wider than the muni heavyweights, so limit orders earn their keep here.
• Launched in 2025 with a modest asset base, so there is little history to judge it by.
• Broad index rivals VTEB and MUB charge 0.03% and 0.05%. This is a pricier, narrower slice of the muni market, and it sits in the lower half of its peer group.

• SUB The five-year ceiling is the whole design, and it cuts both ways: less rate sensitivity, but a shorter stretch of the curve to draw income from than full-maturity muni funds.
• This is a national portfolio. Single-state funds like NYF chase a home-state tax break that a nationwide muni basket cannot offer.
• Broad-maturity peers VTEB and SCMB run at 0.03%. The short-end tilt here costs a few basis points more.

Full MMSD profile⁠

Full SUB profile⁠