SPAXX vs. VMFXX

Last updated Jun 3, 2026

SPAXX (Fidelity Government Money Market Fund) and VMFXX (Vanguard Federal Money Market Fund) are both Money Market funds. Over the past 5 years, SPAXX returned 1.45%/yr vs 2.39%/yr for VMFXX. Their correlation of 0.82 suggests significant overlap in exposure.

Performance

SPAXX vs. VMFXX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Government Money Market Fund (SPAXX) 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, SPAXX achieves a 1.37% return, which is significantly lower than VMFXX's 1.50% return.

SPAXX

• 1D: 0.00%
• 1M: 0.28%
• YTD: 1.37%
• 6M: 1.67%
• 1Y: 3.66%
• 3Y*: 2.42%
• 5Y*: 1.45%
• 10Y*: —

VMFXX

• 1D: 0.00%
• 1M: 0.30%
• YTD: 1.50%
• 6M: 1.82%
• 1Y: 3.95%
• 3Y*: 3.35%
• 5Y*: 2.39%
• 10Y*: —

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

SPAXX vs. VMFXX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021
SPAXX Fidelity Government Money Market Fund	1.37%	3.96%	1.54%	0.41%	0.00%	0.00%
VMFXX Vanguard Federal Money Market Fund	1.50%	4.24%	1.64%	4.64%	0.00%	0.00%

Correlation

The correlation between SPAXX and VMFXX is 1.00 - these two move nearly in lockstep. At this level, holding both provides almost no diversification benefit. If you already own one, adding the other does little to reduce portfolio risk.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	1.00
Correlation (3Y) Calculated over the trailing 3-year period	0.89
Correlation (5Y) Calculated over the trailing 5-year period	0.82
Correlation (All Time) Calculated using the full available price history since May 26, 2021	0.82

The correlation between SPAXX and VMFXX shifts across timeframes, from 0.82 (5 years) to 1.00 (1 year), reflecting how their relationship changes across market environments.

Return for Risk

SPAXX vs. VMFXX - Risk-Adjusted Trends Comparison

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

	SPAXX	VMFXX	Difference
Sharpe ratio Return per unit of total volatility	3.65	3.67	-0.03
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.

SPAXX vs. VMFXX - Sharpe Ratio Comparison

The current SPAXX Sharpe Ratio is 3.65, which is comparable to the VMFXX Sharpe Ratio of 3.67. The chart below compares the historical Sharpe Ratios of SPAXX 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.

Sharpe Ratios by Period

	SPAXX	VMFXX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	3.65	3.67	-0.03
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	2.13	2.60	-0.47
Sharpe Ratio (All Time) Calculated using the full available price history	2.13	2.60	-0.47

Drawdowns

SPAXX vs. VMFXX - Drawdown Comparison

The maximum SPAXX 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 SPAXX and VMFXX.

Drawdown Indicators

	SPAXX	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%
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

SPAXX vs. VMFXX - Volatility Comparison

The current volatility for Fidelity Government Money Market Fund (SPAXX) is 0.28%, while Vanguard Federal Money Market Fund (VMFXX) has a volatility of 0.30%. This indicates that SPAXX 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

	SPAXX	VMFXX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.28%	0.30%	-0.02%
Volatility (6M) Calculated over the trailing 6-month period	0.72%	0.79%	-0.07%
Volatility (1Y) Calculated over the trailing 1-year period	1.03%	1.12%	-0.09%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	0.69%	0.94%	-0.25%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	0.69%	0.94%	-0.25%

Dividends

SPAXX vs. VMFXX - Dividend Comparison

SPAXX's dividend yield for the trailing twelve months is around 3.59%, less than VMFXX's 3.87% yield.

Position	TTM	2025	2024	2023
SPAXX Fidelity Government Money Market Fund	3.59%	3.88%	1.53%	0.41%
VMFXX Vanguard Federal Money Market Fund	3.87%	4.14%	1.63%	4.53%

Frequently Asked Questions

Can I hold both SPAXX and VMFXX in my portfolio?

With a correlation of 1.00, SPAXX and VMFXX move almost identically. Holding both adds very little diversification - you're essentially doubling your position in the same market segment. Choosing one is usually more capital-efficient.

Which is riskier, SPAXX or VMFXX?

VMFXX has higher volatility (0.30%) compared to SPAXX (0.28%). In terms of maximum drawdown, SPAXX dropped 0.00% vs VMFXX's 0.00%.

Which has better risk-adjusted returns?

VMFXX currently has the higher Sharpe Ratio (3.67 vs 3.65), 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.