^CASHX vs. VMFXX

Last updated Jun 24, 2026

^CASHX (US Money Market Index) is an index, while VMFXX (Vanguard Federal Money Market Fund) is Money Market fund managed by Vanguard. Over the past 5 years, ^CASHX returned 3.55%/yr vs 3.02%/yr for VMFXX. At a 0.08 correlation, their price movements are largely independent.

Performance

^CASHX vs. VMFXX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in US Money Market Index (^CASHX) and Vanguard Federal Money Market Fund (VMFXX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, ^CASHX achieves a 1.71% return, which is significantly higher than VMFXX's 1.50% return.

^CASHX

• 1D: 0.01%
• 1M: 0.28%
• YTD: 1.71%
• 6M: 1.79%
• 1Y: 3.87%
• 3Y*: 4.62%
• 5Y*: 3.55%
• 10Y*: 2.33%

VMFXX

• 1D: 0.00%
• 1M: 0.30%
• YTD: 1.50%
• 6M: 1.82%
• 1Y: 3.95%
• 3Y*: 4.42%
• 5Y*: 3.02%
• 10Y*: —

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

^CASHX vs. VMFXX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021
^CASHX US Money Market Index	1.71%	4.21%	5.16%	5.03%	1.68%	0.05%
VMFXX Vanguard Federal Money Market Fund	1.50%	4.24%	4.83%	4.64%	0.00%	0.00%

Correlation

The correlation between ^CASHX and VMFXX is -0.01, 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 (1Y) Calculated over the trailing 1-year period	-0.01
Correlation (3Y) Calculated over the trailing 3-year period	0.00
Correlation (5Y) Calculated over the trailing 5-year period	0.08
Correlation (All Time) Calculated using the full available price history since May 25, 2021	0.08

Return for Risk

^CASHX vs. VMFXX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for US Money Market Index (^CASHX) and Vanguard Federal Money Market Fund (VMFXX). 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.

	^CASHX	VMFXX	Difference
Sharpe ratio: Return per unit of total volatility	263.86	3.67	+260.19
Sortino ratio: Return per unit of downside risk	—	—	—
Omega ratio: Gain probability vs. loss probability	—	—	—
Calmar ratio: Return relative to maximum drawdown	—	—	—
Martin ratio: Return relative to average drawdown	—	—	—

^CASHX vs. VMFXX - Sharpe Ratio Comparison

The current ^CASHX Sharpe Ratio is 263.86, which is higher than the VMFXX Sharpe Ratio of 3.67. The chart below compares the historical Sharpe Ratios of ^CASHX and VMFXX, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Drawdowns

^CASHX vs. VMFXX - Drawdown Comparison

The maximum ^CASHX drawdown since its inception was 0.00%, which is greater than VMFXX's maximum drawdown of 0.00%. Use the drawdown chart below to compare losses from any high point for ^CASHX and VMFXX.

Drawdown Indicators

	^CASHX	VMFXX	Difference
Max Drawdown Largest peak-to-trough decline	0.00%	0.00%	0.00%
Max Drawdown (1Y) Largest decline over 1 year	0.00%	0.00%	0.00%
Max Drawdown (3Y) Largest decline over 3 years	0.00%	0.00%	0.00%
Max Drawdown (5Y) Largest decline over 5 years	0.00%	0.00%	0.00%
Max Drawdown (10Y) Largest decline over 10 years	0.00%	—	—
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%	0.00%	0.00%

Volatility

^CASHX vs. VMFXX - Volatility Comparison

The current volatility for US Money Market Index (^CASHX) is 0.00%, while Vanguard Federal Money Market Fund (VMFXX) has a volatility of 0.30%. This indicates that ^CASHX experiences smaller price fluctuations and is considered to be less risky than VMFXX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	^CASHX	VMFXX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.00%	0.30%	-0.30%
Volatility (6M) Calculated over the trailing 6-month period	0.00%	0.72%	-0.72%
Volatility (1Y) Calculated over the trailing 1-year period	0.01%	1.12%	-1.11%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	0.08%	1.08%	-1.00%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	0.08%	1.07%	-0.99%

Frequently Asked Questions

Can I hold both ^CASHX and VMFXX in my portfolio?

^CASHX and VMFXX have a correlation of -0.01, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, ^CASHX or VMFXX?

VMFXX has higher volatility (0.30%) compared to ^CASHX (0.00%). In terms of maximum drawdown, ^CASHX dropped 0.00% vs VMFXX's 0.00%.

Which has better risk-adjusted returns?

^CASHX currently has the higher Sharpe Ratio (263.86 vs 3.67), meaning it's delivered slightly more return per unit of risk over the trailing 12 months. However, this ranking shifts over time - use the Risk/Return Score above for a more comprehensive view that combines Sharpe, Sortino, and other measures used by quantitative funds.