MSTDX vs. FUMBX

Last updated Jun 23, 2026

MSTDX (MassMutual Short Duration Bond Fund) and FUMBX (Fidelity Short-Term Treasury Bond Index Fund) are both Short-Term Bond funds. Over the past 5 years, MSTDX returned 1.32%/yr vs 1.33%/yr for FUMBX. A 0.50 correlation means they provide meaningful diversification when combined. MSTDX charges 0.51%/yr vs 0.03%/yr for FUMBX.

Performance

MSTDX vs. FUMBX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in MassMutual Short Duration Bond Fund (MSTDX) and Fidelity Short-Term Treasury Bond Index Fund (FUMBX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, MSTDX achieves a 0.73% return, which is significantly higher than FUMBX's -0.01% return.

MSTDX

• 1D: 0.11%
• 1M: 0.33%
• YTD: 0.73%
• 6M: 1.24%
• 1Y: 4.18%
• 3Y*: 5.66%
• 5Y*: 1.32%
• 10Y*: 2.04%

FUMBX

• 1D: 0.10%
• 1M: 0.26%
• YTD: -0.01%
• 6M: 0.34%
• 1Y: 2.99%
• 3Y*: 4.07%
• 5Y*: 1.33%
• 10Y*: —

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

MSTDX vs. FUMBX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
MSTDX MassMutual Short Duration Bond Fund	0.73%	6.18%	6.38%	5.88%	-11.19%	1.79%	2.29%	4.49%	1.68%	0.15%
FUMBX Fidelity Short-Term Treasury Bond Index Fund	-0.01%	5.83%	3.25%	4.47%	-5.84%	-1.38%	4.22%	4.19%	1.47%	-0.33%

Correlation

The correlation between MSTDX and FUMBX is 0.72, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.72
Correlation (3Y) Calculated over the trailing 3-year period	0.76
Correlation (5Y) Calculated over the trailing 5-year period	0.61
Correlation (All Time) Calculated using the full available price history since Oct 19, 2017	0.50

Over the past year, MSTDX and FUMBX have become more correlated (0.72) than their long-term average of 0.50, meaning their price movements have been converging.

Return for Risk

MSTDX vs. FUMBX — Risk / Return Rank

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

MSTDX

MSTDX Risk / Return Rank: 88
MSTDX Sharpe Ratio Rank: 77
MSTDX Sortino Ratio Rank: 93
MSTDX Omega Ratio Rank: 90
MSTDX Calmar Ratio Rank: 87
MSTDX Martin Ratio Rank: 91

FUMBX

FUMBX Risk / Return Rank: 33
FUMBX Sharpe Ratio Rank: 31
FUMBX Sortino Ratio Rank: 37
FUMBX Omega Ratio Rank: 37
FUMBX Calmar Ratio Rank: 32
FUMBX Martin Ratio Rank: 27

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.

MSTDX vs. FUMBX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for MassMutual Short Duration Bond Fund (MSTDX) and Fidelity Short-Term Treasury Bond Index Fund (FUMBX). 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.

	MSTDX	FUMBX	Difference
Sharpe ratio: Return per unit of total volatility	2.35	1.49	+0.86
Sortino ratio: Return per unit of downside risk	4.37	2.35	+2.02
Omega ratio: Gain probability vs. loss probability	1.62	1.30	+0.32
Calmar ratio: Return relative to maximum drawdown	4.05	2.02	+2.03
Martin ratio: Return relative to average drawdown	16.84	5.99	+10.85

MSTDX vs. FUMBX - Sharpe Ratio Comparison

The current MSTDX Sharpe Ratio is 2.35, which is higher than the FUMBX Sharpe Ratio of 1.49. The chart below compares the historical Sharpe Ratios of MSTDX and FUMBX, 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

MSTDX vs. FUMBX - Drawdown Comparison

The maximum MSTDX drawdown since its inception was -13.31%, which is greater than FUMBX's maximum drawdown of -8.83%. Use the drawdown chart below to compare losses from any high point for MSTDX and FUMBX.

Drawdown Indicators

	MSTDX	FUMBX	Difference
Max Drawdown Largest peak-to-trough decline	-13.31%	-8.83%	-4.48%
Max Drawdown (1Y) Largest decline over 1 year	-1.06%	-1.54%	+0.48%
Max Drawdown (3Y) Largest decline over 3 years	-1.06%	-1.57%	+0.51%
Max Drawdown (5Y) Largest decline over 5 years	-13.31%	-8.60%	-4.71%
Max Drawdown (10Y) Largest decline over 10 years	-13.31%	—	—
Current Drawdown Current decline from peak	-0.21%	-0.96%	+0.75%
Average Drawdown Average peak-to-trough decline	-1.43%	-1.85%	+0.42%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.26%	0.52%	-0.26%

Volatility

MSTDX vs. FUMBX - Volatility Comparison

The current volatility for MassMutual Short Duration Bond Fund (MSTDX) is 0.63%, while Fidelity Short-Term Treasury Bond Index Fund (FUMBX) has a volatility of 0.72%. This indicates that MSTDX experiences smaller price fluctuations and is considered to be less risky than FUMBX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	MSTDX	FUMBX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.63%	0.72%	-0.09%
Volatility (6M) Calculated over the trailing 6-month period	1.40%	1.56%	-0.16%
Volatility (1Y) Calculated over the trailing 1-year period	1.83%	2.08%	-0.25%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	2.34%	2.92%	-0.58%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	2.06%	2.49%	-0.43%

MSTDX vs. FUMBX - Expense Ratio Comparison

MSTDX has a 0.51% expense ratio, which is higher than FUMBX's 0.03% expense ratio.

Dividends

MSTDX vs. FUMBX - Dividend Comparison

MSTDX's dividend yield for the trailing twelve months is around 4.44%, more than FUMBX's 3.77% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FUMBX Fidelity Short-Term Treasury Bond Index Fund	3.77%	3.51%	2.91%	1.64%	0.86%	1.15%	1.41%	1.88%	1.64%	0.34%	0.00%	0.00%
MSTDX MassMutual Short Duration Bond Fund	4.44%	4.36%	2.63%	2.48%	1.46%	1.90%	4.44%	3.35%	3.82%	2.51%	2.36%	2.57%

Frequently Asked Questions

Can I hold both MSTDX and FUMBX in my portfolio?

MSTDX and FUMBX have a correlation of 0.72, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, MSTDX or FUMBX?

FUMBX has higher volatility (0.72%) compared to MSTDX (0.63%). In terms of maximum drawdown, MSTDX dropped -13.31% vs FUMBX's -8.83%.

Which has better risk-adjusted returns?

MSTDX currently has the higher Sharpe Ratio (2.35 vs 1.49), 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.