WEEK vs. SPAXX

Last updated Jun 4, 2026

WEEK (Roundhill Weekly T-Bill ETF) and SPAXX (Fidelity Government Money Market Fund) are both funds - WEEK is a Ultrashort Bond fund actively managed by Roundhill, while SPAXX is a Money Market fund actively managed by Fidelity. Both are actively managed. Over the past year, WEEK returned 3.81% vs 3.66% for SPAXX. At a 0.01 correlation, their price movements are largely independent. WEEK charges 0.19%/yr vs 0.42%/yr for SPAXX.

Performance

WEEK vs. SPAXX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Roundhill Weekly T-Bill ETF (WEEK) and Fidelity Government Money Market Fund (SPAXX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

The year-to-date returns for both stocks are quite close, with WEEK having a 1.44% return and SPAXX slightly lower at 1.37%.

WEEK

• 1D: 0.02%
• 1M: 0.28%
• YTD: 1.44%
• 6M: 1.74%
• 1Y: 3.81%
• 3Y*: —
• 5Y*: —
• 10Y*: —

SPAXX

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

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

WEEK vs. SPAXX - Yearly Performance Comparison

	2026 (YTD)	2025
WEEK Roundhill Weekly T-Bill ETF	1.44%	3.37%
SPAXX Fidelity Government Money Market Fund	1.37%	3.29%

Correlation

The correlation between WEEK and SPAXX 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 (All Time) Calculated using the full available price history since Mar 7, 2025	0.01

Return for Risk

WEEK vs. SPAXX — Risk / Return Rank

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

WEEK

WEEK Risk / Return Rank: 99
WEEK Sharpe Ratio Rank: 99
WEEK Sortino Ratio Rank: 99
WEEK Omega Ratio Rank: 99
WEEK Calmar Ratio Rank: 99
WEEK Martin Ratio Rank: 99

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.

WEEK vs. SPAXX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Roundhill Weekly T-Bill ETF (WEEK) 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.

	WEEK	SPAXX	Difference
Sharpe ratio: Return per unit of total volatility	9.29	3.65	+5.64
Sortino ratio: Return per unit of downside risk	19.14	—	—
Omega ratio: Gain probability vs. loss probability	4.65	—	—
Calmar ratio: Return relative to maximum drawdown	29.49	—	—
Martin ratio: Return relative to average drawdown	263.82	—	—
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

WEEK vs. SPAXX - Sharpe Ratio Comparison

The current WEEK Sharpe Ratio is 9.29, which is higher than the SPAXX Sharpe Ratio of 3.65. The chart below compares the historical Sharpe Ratios of WEEK and SPAXX, 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

	WEEK	SPAXX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	9.29	3.65	+5.64
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	—	2.13	—
Sharpe Ratio (All Time) Calculated using the full available price history	10.05	2.13	+7.92

Drawdowns

WEEK vs. SPAXX - Drawdown Comparison

The maximum WEEK drawdown since its inception was -0.13%, which is greater than SPAXX's maximum drawdown of 0.00%. Use the drawdown chart below to compare losses from any high point for WEEK and SPAXX.

Drawdown Indicators

	WEEK	SPAXX	Difference
Max Drawdown Largest peak-to-trough decline	-0.13%	0.00%	-0.13%
Max Drawdown (1Y) Largest decline over 1 year	-0.13%	0.00%	-0.13%
Max Drawdown (3Y) Largest decline over 3 years	—	0.00%	—
Max Drawdown (5Y) Largest decline over 5 years	—	0.00%	—
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-0.01%	0.00%	-0.01%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.01%	0.00%	+0.01%

Volatility

WEEK vs. SPAXX - Volatility Comparison

The current volatility for Roundhill Weekly T-Bill ETF (WEEK) is 0.07%, while Fidelity Government Money Market Fund (SPAXX) has a volatility of 0.28%. This indicates that WEEK 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

	WEEK	SPAXX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.07%	0.28%	-0.21%
Volatility (6M) Calculated over the trailing 6-month period	0.25%	0.72%	-0.47%
Volatility (1Y) Calculated over the trailing 1-year period	0.41%	1.03%	-0.62%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	0.39%	0.69%	-0.30%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	0.39%	0.69%	-0.30%

WEEK vs. SPAXX - Expense Ratio Comparison

WEEK has a 0.19% expense ratio, which is lower than SPAXX's 0.42% expense ratio.

Dividends

WEEK vs. SPAXX - Dividend Comparison

WEEK's dividend yield for the trailing twelve months is around 3.72%, more than SPAXX's 3.59% yield.

Position	TTM	2025	2024	2023
SPAXX Fidelity Government Money Market Fund	3.59%	3.88%	1.53%	0.41%
WEEK Roundhill Weekly T-Bill ETF	3.72%	3.27%	0.00%	0.00%

Frequently Asked Questions

Can I hold both WEEK and SPAXX in my portfolio?

WEEK and SPAXX 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, WEEK or SPAXX?

SPAXX has higher volatility (0.28%) compared to WEEK (0.07%). In terms of maximum drawdown, WEEK dropped -0.13% vs SPAXX's 0.00%.

Which has better risk-adjusted returns?

WEEK currently has the higher Sharpe Ratio (9.29 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.