FXAIX vs FZROX: 86% overlap
Fidelity 500 Index and Fidelity ZERO Total Market Index share 86.5% 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 2 months apart — FXAIX as of 2026-02-28, the rest through 2026-04-30. 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 1.1. Two funds that shared nothing would score 2.0; two identical funds score 1.0.
Top shared holdings
FXAIX and FZROX hold 504 of the same securities. The ten contributing most to the overlap figure:
| Holding | in FXAIX | in FZROX | Δ |
|---|---|---|---|
| NVDA | 7.3% | 6.9% | 0.4% |
| AAPL | 6.6% | 5.7% | 0.9% |
| MSFT | 5.0% | 4.3% | 0.6% |
| AMZN | 3.5% | 3.7% | 0.2% |
| GOOGL | 3.1% | 3.2% | 0.1% |
| AVGO | 2.6% | 2.8% | 0.3% |
| GOOG | 2.5% | 2.6% | 0.1% |
| META | 2.4% | 1.9% | 0.5% |
| TSLA | 1.9% | 1.5% | 0.4% |
| BRK-B | 1.6% | 1.2% | 0.3% |
Where FXAIX and FZROX 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 | FXAIX | FZROX | Δ |
|---|---|---|---|
| Health Care | 9.6% | 8.6% | +1.0pp |
| Industrials | 8.3% | 9.2% | −0.9pp |
| Consumer Staples | 5.4% | 4.6% | +0.7pp |
| Information Technology | 31.8% | 32.3% | −0.5pp |
| Unclassified | 3.3% | 3.8% | −0.5pp |
| Communication Services | 10.5% | 10.1% | +0.4pp |
| Cash and/or Derivatives | 0.3% | 0.6% | −0.4pp |
| Real Estate | 2.0% | 2.3% | −0.3pp |
Δ is FXAIX minus FZROX, 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
0.0% of FXAIX by weight, held in no part of FZROX.
11.8% of FZROX by weight, held in no part of FXAIX.
A large count with a small weight is the usual shape: the positions one fund adds are typically its smallest ones.
Concentration and cost
| FXAIX | FZROX | |
|---|---|---|
| Top 10 holdings | 36.4% | 34.0% |
| Positions held | 506 | 2,685 |
| Cost per $10,000 held, per year | $1 | $0 |
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 FXAIX and FZROX overlap?
FXAIX and FZROX overlap 86.5% by portfolio weight — substantial duplication if you hold both. They share 504 holdings. The figure comes from current issuer holdings files (FXAIX as of 2026-02-28, FZROX as of 2026-04-30).
How is the overlap between FXAIX and FZROX calculated?
As the sum of the smaller weight in each fund, over every holding both funds own: Σ min(wA, wB). If FXAIX holds a stock at 6% and FZROX 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 FXAIX and FZROX?
That depends on your goals — we state facts, not advice. At 86.5% overlap, most of what one fund holds, the other holds too. Expense ratios: FXAIX 0.01% versus FZROX 0.00%.
What does FXAIX own that FZROX doesn't?
FXAIX holds 506 positions and FZROX holds 2,685; 1 of FXAIX's positions don't appear in FZROX at all, and they are 0.0% of FXAIX by weight.
You probably hold more than two funds
This page compares FXAIX and FZROX. 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 FXAIX vs FZROX
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, FXAIX as of 2026-02-28, FZROX as of 2026-04-30. Weights are fractions of each fund. Diagnostics, not advice.