FXAIX vs SPYM: 89% overlap
Fidelity 500 Index and State Street SPDR Portfolio S&P 500 ETF share 88.8% of their portfolios by weight — computed as Σ min(wA, wB) over every holding both funds own.
Different holding dates. These holdings were published about 5 months apart — FXAIX as of 2026-02-28, the rest through 2026-07-23. 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 SPYM hold 462 of the same securities. The ten contributing most to the overlap figure:
| Holding | in FXAIX | in SPYM | Δ |
|---|---|---|---|
| NVDA | 7.3% | 7.9% | 0.6% |
| AAPL | 6.6% | 7.4% | 0.8% |
| MSFT | 5.0% | 4.4% | 0.5% |
| AMZN | 3.5% | 3.6% | 0.1% |
| GOOGL | 3.1% | 2.9% | 0.2% |
| AVGO | 2.6% | 2.9% | 0.4% |
| GOOG | 2.5% | 2.4% | 0.1% |
| META | 2.4% | 2.1% | 0.3% |
| LLY | 1.4% | 1.5% | 0.1% |
| TSLA | 1.9% | 1.4% | 0.5% |
Where FXAIX and SPYM 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 | SPYM | Δ |
|---|---|---|---|
| Information Technology | 31.8% | 37.5% | −5.7pp |
| Unclassified | 3.3% | 0.0% | +3.3pp |
| Communication Services | 10.5% | 9.3% | +1.2pp |
| Consumer Discretionary | 9.7% | 8.7% | +0.9pp |
| Consumer Staples | 5.4% | 4.6% | +0.7pp |
| Industrials | 8.3% | 8.9% | −0.5pp |
| Health Care | 9.6% | 9.1% | +0.4pp |
| Financials | 12.0% | 12.4% | −0.4pp |
Δ is FXAIX minus SPYM, 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
3.5% of FXAIX by weight, held in no part of SPYM.
3.9% of SPYM 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 | SPYM | |
|---|---|---|
| Top 10 holdings | 36.4% | 36.9% |
| Positions held | 506 | 507 |
| Cost per $10,000 held, per year | $1 | $2 |
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 SPYM overlap?
FXAIX and SPYM overlap 88.8% by portfolio weight — substantial duplication if you hold both. They share 462 holdings. The figure comes from current issuer holdings files (FXAIX as of 2026-02-28, SPYM as of 2026-07-23).
How is the overlap between FXAIX and SPYM 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 SPYM 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 SPYM?
That depends on your goals — we state facts, not advice. At 88.8% overlap, most of what one fund holds, the other holds too. Expense ratios: FXAIX 0.01% versus SPYM 0.02%.
What does FXAIX own that SPYM doesn't?
FXAIX holds 506 positions and SPYM holds 507; 43 of FXAIX's positions don't appear in SPYM at all, and they are 3.5% of FXAIX by weight.
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Related comparisons
Sources: issuer holdings files, FXAIX as of 2026-02-28, SPYM as of 2026-07-23. Weights are fractions of each fund. Diagnostics, not advice.