Wealthy PotFSPGX vs FXAIX: A Growth Tilt or the Whole S&P 500?
FSPGX and FXAIX are both low-cost Fidelity index mutual funds with no minimum, and both are full of the biggest U.S. companies. That makes them look like alternatives. They are not. FXAIX owns the entire S&P 500. FSPGX owns only the growth side of large-cap America, tracking the Russell 1000 Growth Index. Choosing between them is choosing whether to make a deliberate bet on growth stocks, and FSPGX also costs more: 0.035% against 0.015%.
The Short Answer
- FXAIX holds the whole S&P 500: growth and value companies alike.
- FSPGX holds only large companies classed as growth, 371 stocks at the latest count.
- FXAIX is cheaper: 0.015% against 0.035%.
- Not a twin: owning FSPGX instead of FXAIX is a style bet, not a like-for-like swap.
FSPGX vs FXAIX Side by Side
| Feature | FSPGX | FXAIX |
|---|---|---|
| Full name | Fidelity Large Cap Growth Index Fund | Fidelity 500 Index Fund |
| Index | Russell 1000 Growth Index | S&P 500 |
| What it holds | Large-cap growth stocks only | All 500 companies in the index |
| Number of holdings | 371 | 500-plus |
| Expense ratio | 0.035% | 0.015% |
| Minimum | $0 | $0 |
Growth Is Half the Market, by Design
FTSE Russell builds the Russell 1000 from the largest U.S. companies, then splits it into a growth index and a value index using measures such as price-to-book, expected earnings growth and historical sales growth. The growth index keeps the companies that score as growth. By construction, it leaves the value half out: banks, energy companies, utilities and other slower-growing businesses that the S&P 500 holds and FSPGX mostly does not.
Because both funds weight by market value, the same giant technology and communication companies sit at the top of each. In FSPGX they make up an even larger share, since the value companies that dilute them in the S&P 500 are gone. That is the bet: FSPGX tends to do better when growth stocks lead and worse when value stocks do, with sharper swings either way. See growth vs value stocks for how those cycles have played out.
The Overlap Trap
A common move is to hold FXAIX as a core and add FSPGX "for growth." That can be a deliberate choice, but know what it does: the biggest growth companies, which make up most of FSPGX, are already in FXAIX, so adding FSPGX doubles your weight in the same names rather than adding much that is new. If that concentration is what you want, the pairing achieves it. If you wanted more diversification, it does the opposite.
Which One Fits You
- Choose FXAIX if you want a core holding in large U.S. companies without a style bet. It is also the cheaper fund.
- Choose FSPGX only if you deliberately want to overweight growth stocks and accept larger swings.
- Holding both is a concentration choice, not diversification. Decide how much extra growth exposure you want and size FSPGX to match.
FAQ
Is FSPGX an S&P 500 fund?
No. FSPGX tracks the Russell 1000 Growth Index, which holds only large companies classed as growth. FXAIX tracks the S&P 500.
Which is cheaper, FSPGX or FXAIX?
FXAIX, at 0.015% a year. FSPGX charges 0.035%.
Does FXAIX already include the stocks in FSPGX?
By value, most of them. Both indexes are drawn from the largest U.S. companies, so the biggest growth names, which carry most of FSPGX's weight, appear in both. The indexes are built differently, so the lists are not identical.
Is FSPGX riskier than FXAIX?
It is more concentrated in one style of company, so it tends to swing more in both directions.
Can I hold FSPGX and FXAIX together?
Yes, as a deliberate tilt toward growth. It increases concentration in the largest growth companies rather than diversifying.
This article is for general information and is not investment advice. Fund figures were taken from Fidelity's published fund pages and can change; confirm current figures before you invest.