AUSM vs SUB

AUSMBAllspring Ultra Short Municipal ETF

SUBAiShares Short-Term National Muni Bond ETF

In short

AUSM An actively run muni cash sleeve in ETF clothing: Allspring aims to keep average effective maturity at one year or less, hunting federally tax-exempt income at the sleepy end of the curve. Fee is 0.19%, with no waiver involved.

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

AUSM The Fund seeks current income exempt from federal income tax while preserving capital. It invests principally in short-term municipal securities and generally expects a dollar-weighted average effective maturity of one year or less.

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

• AUSM Targets a dollar-weighted average effective maturity of one year or less, parking the portfolio at the money-market end of the muni curve, and pays income monthly.sec.gov
• Active, not index-shadowing: the desk works security selection, sector rotation, duration and yield-curve positioning, and may use futures to manage duration.allspringglobal.comsec.gov
• At 0.19% with no waiver involved, the fee lands in line with the typical short-muni fund even though a human team is picking the bonds.
• At least 80% of net assets stay in munis whose interest is exempt from federal income tax, a policy only shareholders can vote to change.sec.gov

• 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

• AUSM Launched in 2025 and thinly traded, so the track record is thin too and spreads can widen when size shows up.
• Index-tracking neighbors cost less: VTES at 0.05% and SUB at 0.07% run short tax-exempt portfolios for a sliver of the price.
• Up to 20% of assets can pay AMT-subject interest and up to 10% can sit below investment grade, so tax-exempt is not absolute and credit risk is not zero.sec.gov

• 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 AUSM profile⁠

Full SUB profile⁠