PMMF vs SPY
iShares Prime Money Market ETF vs State Street SPDR S&P 500 ETF Trust
Which is better, PMMF or SPY?
SPY has been ahead.
SPY has a lower expense ratio. SPY led over 1Y and the full window.
MarketXLS is not an investment adviser. This comparison is generated automatically from market data and is for information only. A Best mark means the better reading on that one measure, not a recommendation to buy.
Side-by-Side Comparison
| Metric | PMMF | SPY |
|---|---|---|
| Expense Ratio | 0.20% | 0.09%Best |
| AUM | $725M | $804.7B |
| Dividend Yield | 3.97% | 0.98% |
| Holdings | 248 | 505 |
| YTD Return | +2.49% | +10.96%Best |
| 1Y Return | +3.71% | +15.52%Best |
| 3Y Return (annualized) | - | +20.73% |
| 5Y Return (annualized) | - | +12.53% |
| Volatility (annualized) | 0.7%Best | 13.3% |
| Max Drawdown | -0.3%Best | -18.8% |
| $10,000 over 1.6 years | $10,641 | $12,675Best |
| Fund Family | iShares by BlackRock (US) | State Street Investment Management |
| Category | Money Market | Equity |
| Style | - | Large Cap Blend |
| Inception | Feb 4, 2025 | Jan 22, 1993 |
Not shown on this pair: Top 10 Weight.
Volatility and max drawdown, and the $10,000 over 1.6 years row, are measured over the window both funds cover: Feb 5, 2025 to Sep 16, 2026 (1.6 years).
PMMF vs SPY growth
Month-end closes. Both lines start at 0% in the first month shown, so the gap between them is the difference in growth across that window. The full view covers the 1.6 years both funds cover.
PMMF vs SPY Performance
iShares Prime Money Market ETF (PMMF) is an ETF from iShares by BlackRock (US) and State Street SPDR S&P 500 ETF Trust (SPY) is an ETF from State Street Investment Management. Over the past year PMMF returned +3.71% while SPY returned +15.52%. Year to date, PMMF is up 2.49% versus a gain of 10.96% for SPY.
Past performance does not guarantee future results.
Risk: Volatility and Drawdowns
SPY has been the more volatile fund, with annualized monthly volatility of 13.3% compared with 0.7% for PMMF. Lower volatility generally means a smoother ride, though it often comes with lower long-run returns.
The deepest peak-to-trough decline in our data was -0.3% for PMMF and -18.8% for SPY. Drawdown depth is what each fund did in the worst stretch of the window measured above.
The two funds' monthly returns correlate at 0.20. They move largely independently of each other.
Fees and Cost Over Time
PMMF charges 0.20% per year while SPY charges 0.09%. On a $10,000 position that is $20 vs $9 annually, a gap of $11 per year that compounds over a long holding period. On income, PMMF currently yields 3.97% against 0.98% for SPY.
You are not choosing between two funds in isolation.
Whichever of PMMF and SPY you pick has to sit alongside everything else you own. Add the rest and see what the combination actually holds.
Free for up to 10 holdings. No account needed.
Frequently Asked Questions
Which is cheaper, PMMF or SPY?
PMMF has an expense ratio of 0.20% while SPY charges 0.09%. SPY is the cheaper option, by $11 a year on a $10,000 investment.
Which performed better, PMMF or SPY?
Over the past year PMMF returned +3.71% vs +15.52% for SPY, so SPY leads on 1-year performance. Over the longest common window we track (2 years), PMMF annualized +3.96% vs +15.97% for SPY. Past performance does not guarantee future results. This is information, not a recommendation.
Which is riskier, PMMF or SPY?
SPY has been the more volatile fund at 13.3% annualized versus 0.7% for PMMF. Worst drawdown: PMMF -0.3% vs SPY -18.8%.
Should I hold both PMMF and SPY?
PMMF and SPY have a monthly-return correlation of 0.20, so their returns are far enough apart for the mix to behave differently from either one alone. This is information, not a recommendation.
Which pays a higher dividend, PMMF or SPY?
PMMF yields 3.97% while SPY yields 0.98%, so PMMF currently pays the higher dividend yield.
Is SPY better than PMMF?
SPY has a lower expense ratio. SPY led over 1Y and the full window. Which one suits a particular account depends on what it is for. This is information, not a recommendation.