VFIAX vs VIMAX: 17% overlap
Vanguard 500 Index Admiral and Vanguard Mid-Cap Index Admiral share 16.6% of their portfolios by weight — computed as Σ min(wA, wB) over every holding both funds own.
You would hold two tickers and get the diversification of 1.8. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
VFIAX and VIMAX hold 249 of the same securities. The ten contributing most to the overlap figure:
| Holding | in VFIAX | in VIMAX | Δ |
|---|---|---|---|
| WDC | 0.3% | 1.1% | 0.7% |
| STX | 0.3% | 1.0% | 0.7% |
| CASH | 0.2% | 0.5% | 0.3% |
| VRT | 0.2% | 1.2% | 1.0% |
| PWR | 0.2% | 1.0% | 0.9% |
| HWM | 0.2% | 1.0% | 0.9% |
| NEM | 0.2% | 0.5% | 0.3% |
| CMI | 0.2% | 1.0% | 0.8% |
| FTNT | 0.1% | 0.5% | 0.3% |
| WMB | 0.1% | 0.4% | 0.3% |
Where VFIAX 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 | VFIAX | VIMAX | Δ |
|---|---|---|---|
| Information Technology | 38.0% | 16.1% | +21.9pp |
| Industrials | 8.9% | 19.6% | −10.7pp |
| Communication Services | 9.7% | 2.8% | +6.9pp |
| Utilities | 2.2% | 8.4% | −6.2pp |
| Energy | 3.0% | 7.3% | −4.3pp |
| Real Estate | 1.8% | 5.1% | −3.2pp |
| Materials | 1.8% | 4.3% | −2.5pp |
| Financials | 11.6% | 14.0% | −2.4pp |
Δ is VFIAX 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
83.4% of VFIAX by weight, held in no part of VIMAX.
8.6% of VIMAX by weight, held in no part of VFIAX.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| VFIAX | VIMAX | |
|---|---|---|
| Top 10 holdings | 36.4% | 9.5% |
| Positions held | 505 | 283 |
| Cost per $10,000 held, per year | $4 | $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 VFIAX and VIMAX overlap?
VFIAX and VIMAX overlap 16.6% by portfolio weight — moderate overlap. They share 249 holdings. The figure comes from current issuer holdings files (VFIAX as of 2026-06-30, VIMAX as of 2026-06-30).
How is the overlap between VFIAX and VIMAX calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If VFIAX 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 VFIAX and VIMAX?
That depends on your goals — we state facts, not advice. At 16.6% overlap, each fund still contributes meaningfully distinct exposure.
What does VFIAX own that VIMAX doesn't?
VFIAX holds 505 positions and VIMAX holds 283; 256 of VFIAX's positions don't appear in VIMAX at all, and they are 83.4% of VFIAX by weight.
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Related comparisons
Sources: issuer holdings files, VFIAX as of 2026-06-30, VIMAX as of 2026-06-30. Weights are fractions of each fund. Diagnostics, not advice.