MUB vs VBIAX: 0% overlap
iShares National Muni Bond ETF and Vanguard Balanced Index Admiral share 0.1% of their portfolios by weight — computed as Σ min(wA, wB) over every holding both funds own.
Different holding dates. These holdings were published about 4 months apart — VBIAX as of 2026-03-31, the rest through 2026-07-23. Each fund is compared using its most recent file, so any trading in between shows up as a difference.
You would hold two tickers and get the diversification of 2.0. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
MUB and VBIAX hold 78 of the same securities. The ten contributing most to the overlap figure:
| Holding | in MUB | in VBIAX | Δ |
|---|---|---|---|
| 73358W | 0.2% | 0.0% | 0.2% |
| 64966S | 1.1% | 0.0% | 1.1% |
| 646139 | 0.1% | 0.0% | 0.1% |
| 626207 | 0.0% | 0.0% | 0.0% |
| 64972F | 0.1% | 0.0% | 0.1% |
| 072024 | 0.4% | 0.0% | 0.4% |
| 91412H | 1.6% | 0.0% | 1.6% |
| 13063D | 2.7% | 0.0% | 2.7% |
| 914455 | 0.0% | 0.0% | 0.0% |
| 13077D | 0.4% | 0.0% | 0.4% |
Where MUB and VBIAX differ
Sector weights as a share of each fund, ordered by the size of the gap rather than the size of the sector — two funds that overlap heavily still usually diverge somewhere.
| Sector | MUB | VBIAX | Δ |
|---|---|---|---|
| Unclassified | 0.0% | 55.1% | −55.1pp |
| State Tax-Backed | 30.7% | 0.0% | +30.7pp |
| Treasuries | 0.0% | 19.1% | −19.1pp |
| Utilities | 16.8% | 1.2% | +15.6pp |
| Local Tax-Backed | 14.9% | 0.0% | +14.9pp |
| School Districts | 10.2% | 0.0% | +10.2pp |
| Transportation | 10.2% | 0.0% | +10.1pp |
| Education | 8.7% | 0.0% | +8.7pp |
Δ is MUB minus VBIAX, in percentage points. Sector data is not published by every issuer, so “Unclassified” is a real category rather than a gap in the table.
What each fund holds alone
74.8% of MUB by weight, held in no part of VBIAX.
99.0% of VBIAX by weight, held in no part of MUB.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| MUB | VBIAX | |
|---|---|---|
| Top 10 holdings | 17.2% | 45.2% |
| Positions held | 969 | 5,119 |
| Cost per $10,000 held, per year | $5 | $7 |
Cost is the expense ratio applied to $10,000; it excludes any brokerage commission, bid-ask spread or tax consequence. Figures are facts about the funds, not a suggestion about which to hold.
Frequently asked
How much do MUB and VBIAX overlap?
MUB and VBIAX overlap 0.1% by portfolio weight — largely distinct portfolios. They share 78 holdings. The figure comes from current issuer holdings files (MUB as of 2026-07-23, VBIAX as of 2026-03-31).
How is the overlap between MUB and VBIAX calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If MUB holds a stock at 6% and VBIAX holds the same stock at 4%, 4% counts as shared. The result is bounded between 0% and 100%, and it is computed after looking through any fund-of-funds to the underlying holdings.
Is it redundant to hold both MUB and VBIAX?
That depends on your goals — we state facts, not advice. At 0.1% overlap, each fund still contributes meaningfully distinct exposure.
What does MUB own that VBIAX doesn't?
MUB holds 969 positions and VBIAX holds 5,119; 890 of MUB's positions don't appear in VBIAX at all, and they are 74.8% of MUB by weight.
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Related comparisons
Sources: issuer holdings files, MUB as of 2026-07-23, VBIAX as of 2026-03-31. Weights are fractions of each fund. Diagnostics, not advice.