^CASHX vs. SPAXX

Last updated Apr 1, 2026

Compare and contrast key facts about US Money Market Index (^CASHX) and Fidelity Government Money Market Fund (SPAXX).

SPAXX is managed by Fidelity. It was launched on Feb 5, 1990.

Performance

^CASHX vs. SPAXX - Performance Comparison

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

^CASHX vs. SPAXX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021
^CASHX US Money Market Index	0.88%	4.21%	5.16%	5.03%	1.68%	0.05%
SPAXX Fidelity Government Money Market Fund	0.53%	3.96%	1.54%	0.41%	0.00%	0.00%

Returns By Period

In the year-to-date period, ^CASHX achieves a 0.88% return, which is significantly higher than SPAXX's 0.53% return.

^CASHX

• 1D: 0.01%
• 1M: 0.28%
• YTD: 0.88%
• 6M: 1.85%
• 1Y: 4.03%
• 3Y*: 4.72%
• 5Y*: 3.39%
• 10Y*: 2.25%

SPAXX

• 1D: 0.00%
• 1M: 0.00%
• YTD: 0.53%
• 6M: 1.46%
• 1Y: 3.49%
• 3Y*: 2.14%
• 5Y*: —
• 10Y*: —

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

Return for Risk

^CASHX vs. SPAXX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for US Money Market Index (^CASHX) and Fidelity Government Money Market Fund (SPAXX). 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.

	^CASHX	SPAXX	Difference
Sharpe ratio Return per unit of total volatility	266.24	3.65	+262.59
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	—	—	—
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

^CASHX vs. SPAXX - Sharpe Ratio Comparison

The current ^CASHX Sharpe Ratio is 266.24, which is higher than the SPAXX Sharpe Ratio of 3.65. The chart below compares the historical Sharpe Ratios of ^CASHX and SPAXX, offering insights into how both investments have performed under varying market conditions. These values are calculated using daily returns over the previous 12 months.

Sharpe Ratios by Period

	^CASHX	SPAXX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	266.24	3.65	+262.59
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	33.33	—	—
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	23.26	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	25.97	2.01	+23.96

Correlation

The correlation between ^CASHX and SPAXX is 0.01, which is considered to be low. This implies their price changes are not closely related. A low correlation is generally favorable for portfolio diversification, as it helps to reduce overall risk by spreading it across multiple assets with different performance patterns.

Drawdowns

^CASHX vs. SPAXX - Drawdown Comparison

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

Drawdown Indicators

	^CASHX	SPAXX	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 (5Y) Largest decline over 5 years	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. SPAXX - Volatility Comparison

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

Volatility by Period

	^CASHX	SPAXX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.00%	0.00%	0.00%
Volatility (6M) Calculated over the trailing 6-month period	0.01%	0.71%	-0.70%
Volatility (1Y) Calculated over the trailing 1-year period	0.01%	1.08%	-1.07%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	0.08%	0.67%	-0.59%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	0.08%	0.67%	-0.59%