Wealthy PotSPRXX vs SPAXX (2026)
Two Fidelity funds again: SPRXX is a prime fund (slightly higher yield, a touch more credit risk, no state-tax break) and SPAXX is the government sweep (lower risk, automatic, partly state-tax-exempt). Choose SPRXX to nudge the yield up on cash you actively manage, SPAXX for the safer, hands-off default.
By Wealthy Pot · Last updated September 2026
| Feature | SPRXX | SPAXX |
|---|---|---|
| Provider | Fidelity | Fidelity |
| Fund type | Prime | Government |
| 7-day yield | 3.36% (7-day SEC yield) | 3.34% (7-day SEC yield) |
| Expense ratio | 0.42% | 0.42% |
| Minimum | $0 | $0 |
| State tax | Mostly taxable (14.6% U.S. government obligations, 2025 — a prime fund holds corporate paper) | Partly state-tax-exempt (50.9% U.S. government obligations, 2025 — below the CA/CT/NY threshold) |
| Auto-sweep? | No — a purchased position, not a core sweep | Yes — a default core/sweep position at Fidelity |
| Best for | Fidelity investors who want a slightly higher prime-fund yield and accept minor extra risk | Fidelity customers who want their idle cash to earn a yield automatically |
Where SPRXX wins
- A prime fund that typically yields a bit more than government funds
- No minimum investment
- Broad diversification of short-term instruments
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?
Two Fidelity funds again: SPRXX is a prime fund (slightly higher yield, a touch more credit risk, no state-tax break) and SPAXX is the government sweep (lower risk, automatic, partly state-tax-exempt). Choose SPRXX to nudge the yield up on cash you actively manage, SPAXX for the safer, hands-off default.
Compare these against every fund in our money-market fund comparison.
We summarize the funds' published facts, not user reviews. 7-day yields are variable, change daily, and are re-checked against each fund's official page. Money-market funds are not FDIC-insured. Some outbound links may be affiliate links — that never affects our comparisons. Nothing here is financial advice.