FXNAX vs VBIAX: 39% overlap
Fidelity U.S. Bond Index and Vanguard Balanced Index Admiral share 38.6% of their portfolios by weight — computed as Σ min(wA, wB) over every holding both funds own.
Different holding dates. These holdings were published 31 days apart — FXNAX as of 2026-02-28, the rest through 2026-03-31. 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 1.6. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
FXNAX and VBIAX hold 844 of the same securities. The ten contributing most to the overlap figure:
| Holding | in FXNAX | in VBIAX | Δ |
|---|---|---|---|
| UST | 45.4% | 19.1% | 26.3% |
| AGENCY-MBS | 16.5% | 8.1% | 8.4% |
| CASH | 1.3% | 1.8% | 0.5% |
| 46647P | 0.6% | 0.2% | 0.3% |
| 06051G | 0.6% | 0.2% | 0.4% |
| 68389X | 0.4% | 0.1% | 0.2% |
| 61747Y | 0.2% | 0.1% | 0.1% |
| 459058 | 0.1% | 0.1% | 0.0% |
| 95000U | 0.3% | 0.1% | 0.2% |
| 38141G | 0.4% | 0.1% | 0.3% |
Where FXNAX 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 | FXNAX | VBIAX | Δ |
|---|---|---|---|
| Unclassified | 9.5% | 55.1% | −45.6pp |
| Treasuries | 45.4% | 19.1% | +26.3pp |
| MBS Pass-Through | 16.5% | 8.1% | +8.4pp |
| Corporate — industrial & other | 14.1% | 5.8% | +8.4pp |
| Financials | 8.6% | 3.6% | +5.0pp |
| Utilities | 2.5% | 1.2% | +1.3pp |
| Health Care | 0.0% | 1.2% | −1.2pp |
| Information Technology | 0.0% | 1.0% | −1.0pp |
Δ is FXNAX 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
9.2% of FXNAX by weight, held in no part of VBIAX.
61.6% of VBIAX by weight, held in no part of FXNAX.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| FXNAX | VBIAX | |
|---|---|---|
| Top 10 holdings | 69.4% | 45.2% |
| Positions held | 1,266 | 5,119 |
| Cost per $10,000 held, per year | $3 | $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 FXNAX and VBIAX overlap?
FXNAX and VBIAX overlap 38.6% by portfolio weight — moderate overlap. They share 844 holdings. The figure comes from current issuer holdings files (FXNAX as of 2026-02-28, VBIAX as of 2026-03-31).
How is the overlap between FXNAX and VBIAX calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If FXNAX 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 FXNAX and VBIAX?
That depends on your goals — we state facts, not advice. At 38.6% overlap, each fund still contributes meaningfully distinct exposure.
What does FXNAX own that VBIAX doesn't?
FXNAX holds 1,266 positions and VBIAX holds 5,119; 422 of FXNAX's positions don't appear in VBIAX at all, and they are 9.2% of FXNAX by weight.
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Related comparisons
Sources: issuer holdings files, FXNAX as of 2026-02-28, VBIAX as of 2026-03-31. Weights are fractions of each fund. Diagnostics, not advice.