VBIAX vs VIMAX: 1% overlap
Vanguard Balanced Index Admiral and Vanguard Mid-Cap Index Admiral share 1.5% 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 3 months apart — VBIAX as of 2026-03-31, the rest through 2026-06-30. 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
VBIAX and VIMAX hold 24 of the same securities. The ten contributing most to the overlap figure:
| Holding | in VBIAX | in VIMAX | Δ |
|---|---|---|---|
| CASH | 1.8% | 0.5% | 1.3% |
| WDC | 0.1% | 1.1% | 1.0% |
| CEG | 0.1% | 0.8% | 0.7% |
| VLO | 0.1% | 0.7% | 0.7% |
| GM | 0.1% | 0.7% | 0.6% |
| LHX | 0.1% | 0.5% | 0.5% |
| NET | 0.1% | 0.8% | 0.7% |
| TEL | 0.1% | 0.6% | 0.5% |
| EA | 0.0% | 0.5% | 0.4% |
| ETR | 0.0% | 0.5% | 0.5% |
Where VBIAX and VIMAX 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 | VBIAX | VIMAX | Δ |
|---|---|---|---|
| Unclassified | 55.1% | 0.4% | +54.7pp |
| Treasuries | 19.1% | 0.0% | +19.1pp |
| Industrials | 0.7% | 19.6% | −18.9pp |
| Information Technology | 1.0% | 16.1% | −15.1pp |
| Financials | 3.6% | 14.0% | −10.4pp |
| Consumer Discretionary | 0.5% | 8.9% | −8.4pp |
| MBS Pass-Through | 8.1% | 0.0% | +8.1pp |
| Energy | 0.1% | 7.3% | −7.2pp |
Δ is VBIAX minus VIMAX, 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
98.1% of VBIAX by weight, held in no part of VIMAX.
88.7% of VIMAX by weight, held in no part of VBIAX.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| VBIAX | VIMAX | |
|---|---|---|
| Top 10 holdings | 45.2% | 9.5% |
| Positions held | 5,119 | 283 |
| Cost per $10,000 held, per year | $7 | $5 |
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 VBIAX and VIMAX overlap?
VBIAX and VIMAX overlap 1.5% by portfolio weight — largely distinct portfolios. They share 24 holdings. The figure comes from current issuer holdings files (VBIAX as of 2026-03-31, VIMAX as of 2026-06-30).
How is the overlap between VBIAX and VIMAX calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If VBIAX holds a stock at 6% and VIMAX 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 VBIAX and VIMAX?
That depends on your goals — we state facts, not advice. At 1.5% overlap, each fund still contributes meaningfully distinct exposure.
What does VBIAX own that VIMAX doesn't?
VBIAX holds 5,119 positions and VIMAX holds 283; 5,094 of VBIAX's positions don't appear in VIMAX at all, and they are 98.1% of VBIAX by weight.
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Related comparisons
Sources: issuer holdings files, VBIAX as of 2026-03-31, VIMAX as of 2026-06-30. Weights are fractions of each fund. Diagnostics, not advice.