PMMF vs. MMK

Last updated Jul 14, 2026

PMMF (iShares Prime Money Market ETF) and MMK (State Street Prime Money Market ETF) are both Money Market funds. Both are actively managed. At a correlation of -0.04, they often move in opposite directions. PMMF charges 0.20%/yr vs 0.18%/yr for MMK.

Performance

PMMF vs. MMK - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in iShares Prime Money Market ETF (PMMF) and State Street Prime Money Market ETF (MMK). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

PMMF

• 1D: 0.03%
• 1M: 0.30%
• 6M: 1.80%
• YTD: 1.92%
• 1Y: 3.93%
• 3Y*: —
• 5Y*: —
• 10Y*: —

MMK

• 1D: 0.00%
• 1M: 0.28%
• 6M: —
• YTD: —
• 1Y: —
• 3Y*: —
• 5Y*: —
• 10Y*: —

*Multi-year figures are annualized to reflect compound growth (CAGR)

PMMF vs. MMK - Yearly Performance Comparison

	2026 (YTD)
PMMF iShares Prime Money Market ETF	1.48%
MMK State Street Prime Money Market ETF	1.49%

Correlation

The correlation between PMMF and MMK is -0.04, meaning there is essentially no relationship between their price movements. Each responds to its own set of market drivers, making them strong candidates for combining in a diversified portfolio.

	Correlation
Correlation (All Time) Calculated using the full available price history since Feb 12, 2026	-0.04

Return for Risk

PMMF vs. MMK — Risk / Return Rank

Compare risk-adjusted metric ranks to identify better-performing investments over the past 12 months.

PMMF

PMMF Risk / Return Rank: 100
PMMF Sharpe Ratio Rank: 100
PMMF Sortino Ratio Rank: 100
PMMF Omega Ratio Rank: 100
PMMF Calmar Ratio Rank: 100
PMMF Martin Ratio Rank: 100

MMK

Risk / return metrics aren't available yet — we need at least 12 months of trading data to calculate them.

The rank (0–100) shows how this investment's returns compare to the risk taken. Higher = better. Based on the past 12 months of data, combining Sharpe, Sortino, and other metrics used by quantitative funds and institutional investors.

PMMF vs. MMK - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for iShares Prime Money Market ETF (PMMF) and State Street Prime Money Market ETF (MMK). Risk-adjusted metrics are performance indicators that assess an investment's returns in relation to its risk, enabling a more accurate comparison of different investment options.

Values are calculated on a 1-year rolling basis and updated daily. Risk-adjusted metrics are more stable over longer periods — use the period switch above to explore them.

	PMMF	MMK	Difference
Sharpe ratio: Return per unit of total volatility	20.52	—	—
Sortino ratio: Return per unit of downside risk	98.03	—	—
Omega ratio: Gain probability vs. loss probability	41.61	—	—
Calmar ratio: Return relative to maximum drawdown	158.48	—	—
Martin ratio: Return relative to average drawdown	1,526.66	—	—

Drawdowns

PMMF vs. MMK - Drawdown Comparison

The maximum PMMF drawdown since its inception was -0.13%, which is greater than MMK's maximum drawdown of -0.01%. Use the drawdown chart below to compare losses from any high point for PMMF and MMK.

Drawdown Indicators

	PMMF	MMK	Difference
Max Drawdown Largest peak-to-trough decline	-0.13%	-0.01%	-0.12%
Max Drawdown (1Y) Largest decline over 1 year	-0.02%	—	—
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-0.00%	-0.00%	0.00%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.00%	—	—

Volatility

Volatility by Period

	PMMF	MMK	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.05%	—	—
Volatility (6M) Calculated over the trailing 6-month period	0.13%	—	—
Volatility (1Y) Calculated over the trailing 1-year period	0.19%	0.18%	+0.01%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	0.35%	0.18%	+0.17%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	0.35%	0.18%	+0.17%

PMMF vs. MMK - Expense Ratio Comparison

PMMF has a 0.20% expense ratio, which is higher than MMK's 0.18% expense ratio. However, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

PMMF vs. MMK - Dividend Comparison

PMMF's dividend yield for the trailing twelve months is around 3.85%, more than MMK's 1.38% yield.

Position	TTM	2025
MMK State Street Prime Money Market ETF	1.38%	0.00%
PMMF iShares Prime Money Market ETF	3.85%	3.59%

Frequently Asked Questions

Can I hold both PMMF and MMK in my portfolio?

PMMF and MMK have a correlation of -0.04, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which ETF is better, PMMF or MMK?

On fees, MMK is cheaper at 0.18% per year. The better choice depends on whether you care most about return, fees, risk, or income.

Which ETF is cheaper, PMMF or MMK?

MMK is cheaper with a 0.18% expense ratio, compared with 0.20% for PMMF.

Which ETF pays a higher dividend yield, PMMF or MMK?

PMMF has the higher dividend yield at 3.85%, compared with 1.38% for MMK.

What is the main difference between PMMF and MMK?

They also come from different issuers: BlackRock and State Street. Their fees differ too: 0.20% for PMMF and 0.18% for MMK.