ABALX vs FXAIX: 30% overlap
American Funds American Balanced A and Fidelity 500 Index share 29.8% 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 — FXAIX 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 1.7. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
ABALX and FXAIX hold 112 of the same securities. The ten contributing most to the overlap figure:
| Holding | in ABALX | in FXAIX | Δ |
|---|---|---|---|
| AVGO | 3.4% | 2.6% | 0.8% |
| NVDA | 2.0% | 7.3% | 5.3% |
| MSFT | 2.0% | 5.0% | 3.0% |
| GOOGL | 1.7% | 3.1% | 1.3% |
| GOOG | 1.4% | 2.5% | 1.0% |
| LLY | 1.3% | 1.4% | 0.1% |
| V | 1.0% | 0.9% | 0.1% |
| AMZN | 0.8% | 3.5% | 2.7% |
| MU | 1.3% | 0.8% | 0.5% |
| META | 0.7% | 2.4% | 1.7% |
Where ABALX and FXAIX 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 | ABALX | FXAIX | Δ |
|---|---|---|---|
| Unclassified | 22.7% | 3.3% | +19.4pp |
| Information Technology | 16.0% | 31.8% | −15.8pp |
| Treasuries | 12.3% | 0.0% | +12.3pp |
| Communication Services | 5.1% | 10.5% | −5.4pp |
| Consumer Discretionary | 4.7% | 9.7% | −4.9pp |
| Corporate — industrial & other | 3.6% | 0.0% | +3.6pp |
| Financials | 8.9% | 12.0% | −3.1pp |
| Health Care | 6.7% | 9.6% | −2.9pp |
Δ is ABALX minus FXAIX, 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
55.8% of ABALX by weight, held in no part of FXAIX.
38.5% of FXAIX by weight, held in no part of ABALX.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| ABALX | FXAIX | |
|---|---|---|
| Top 10 holdings | 36.3% | 36.4% |
| Positions held | 1,439 | 506 |
| Cost per $10,000 held, per year | $56 | $1 |
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 ABALX and FXAIX overlap?
ABALX and FXAIX overlap 29.8% by portfolio weight — moderate overlap. They share 112 holdings. The figure comes from current issuer holdings files (ABALX as of 2026-03-31, FXAIX as of 2026-02-28).
How is the overlap between ABALX and FXAIX calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If ABALX holds a stock at 6% and FXAIX 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 ABALX and FXAIX?
That depends on your goals — we state facts, not advice. At 29.8% overlap, each fund still contributes meaningfully distinct exposure.
What does ABALX own that FXAIX doesn't?
ABALX holds 1,439 positions and FXAIX holds 506; 1,326 of ABALX's positions don't appear in FXAIX at all, and they are 55.8% of ABALX by weight.
You probably hold more than two funds
This page compares ABALX and FXAIX. Paste your whole portfolio — brokerage, 401(k), IRA — and see the overlap across every fund at once, plus what you actually own underneath them and your own Effective Funds number. Free, no account, nothing stored.
X-ray my portfolio — free →Watch ABALX vs FXAIX
We re-read both funds’ published holdings every weeknight. Leave an address and we'll tell you when what's inside actually changes.
Not sending yet — email alerts are built but switched off, and you'll be among the first when they turn on. No spam, one-click unsubscribe.
Related comparisons
Sources: issuer holdings files, ABALX as of 2026-03-31, FXAIX as of 2026-02-28. Weights are fractions of each fund. Diagnostics, not advice.