Wealthy PotFDRXX vs SPAXX (2026)
Nearly the same fund. Both are Fidelity government money-market funds that can sit in your core position, and their holdings and yields track each other closely. FDRXX carries the lower expense ratio (0.35% against SPAXX’s 0.42%), so it usually nets slightly more. The catch is availability: SPAXX is the default core almost everywhere, while FDRXX is not always offered as a core choice. If you can select FDRXX, take it; if you cannot, the gap is small enough that SPAXX is no mistake.
By Wealthy Pot · Last updated September 2026
| Feature | FDRXX | SPAXX |
|---|---|---|
| Provider | Fidelity | Fidelity |
| Wrapper | Money-market fund | Money-market fund |
| Holdings type | Government | Government |
| 7-day SEC yield | 3.40% (7-day SEC yield) | 3.34% (7-day SEC yield) |
| Share price | Stable $1.00 NAV (targeted, not guaranteed) | Stable $1.00 NAV (targeted, not guaranteed) |
| Expense ratio | 0.35% | 0.42% |
| Minimum | $0 | $0 |
| State tax | Partly state-tax-exempt (52.2% U.S. government obligations, 2025 — below the CA/CT/NY threshold) | Partly state-tax-exempt (50.9% U.S. government obligations, 2025 — below the CA/CT/NY threshold) |
| Auto-sweep? | Yes — available as a Fidelity core position | Yes — a default core/sweep position at Fidelity |
| Best for | Fidelity customers who want a government sweep, often a touch higher net yield than SPAXX | Fidelity customers who want their idle cash to earn a yield automatically |
Where FDRXX wins
- A government sweep alternative to SPAXX that often nets a slightly higher yield
Where SPAXX wins
- The default Fidelity core/sweep position — idle cash earns automatically
- No minimum investment
- Government fund (holds government debt and repos), lower credit risk than prime
- Portion of income is state-tax-exempt
Which should you choose?
Nearly the same fund. Both are Fidelity government money-market funds that can sit in your core position, and their holdings and yields track each other closely. FDRXX carries the lower expense ratio (0.35% against SPAXX’s 0.42%), so it usually nets slightly more. The catch is availability: SPAXX is the default core almost everywhere, while FDRXX is not always offered as a core choice. If you can select FDRXX, take it; if you cannot, the gap is small enough that SPAXX is no mistake.
Compare these against every fund in our money-market fund comparison.
We summarize the funds' published facts, not user reviews. Yields are variable, change daily, and are re-checked against each fund's official page. Neither money-market funds nor ETFs are FDIC-insured, and an ETF's share price can fall as well as rise. Some outbound links may be affiliate links — that never affects our comparisons. Nothing here is financial advice.