FUMBX vs. ISTB

Last updated Aug 1, 2026

FUMBX (Fidelity Short-Term Treasury Bond Index Fund) and ISTB (iShares Core 1-5 Year USD Bond ETF) are both Short-Term Bond funds - FUMBX tracks the Bloomberg U.S. 1-5 Year Treasury Bond Index while ISTB tracks the BBG US Universal 1-5 Year Index (USD). Both are passively managed. Over the past 5 years, FUMBX returned 1.26%/yr vs 1.86%/yr for ISTB. Their 0.78 correlation means they have sometimes moved together and sometimes differently. FUMBX charges 0.03%/yr vs 0.06%/yr for ISTB.

Performance

FUMBX vs. ISTB - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Short-Term Treasury Bond Index Fund (FUMBX) and iShares Core 1-5 Year USD Bond ETF (ISTB). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, FUMBX achieves a 0.15% return, which is significantly lower than ISTB's 0.63% return.

FUMBX

• 1D: 0.00%
• 1M: -0.29%
• 6M: -0.01%
• YTD: 0.15%
• 1Y: 1.98%
• 3Y*: 4.11%
• 5Y*: 1.26%
• 10Y*: —
• ALL TIME*: 1.76%

ISTB

• 1D: -0.04%
• 1M: -0.19%
• 6M: 0.35%
• YTD: 0.63%
• 1Y: 2.74%
• 3Y*: 4.99%
• 5Y*: 1.86%
• 10Y*: 2.20%
• ALL TIME*: 2.01%

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

Liquidity Comparison

Position	Avg. Volume Value (2W)	Avg. Volume Value (1M)	Avg. Volume Value (3M)
FUMBX Fidelity Short-Term Treasury Bond Index Fund	$0.00	$0.00	$0.00
ISTB iShares Core 1-5 Year USD Bond ETF	$20.52M	$19.72M	$25.64M

FUMBX vs. ISTB - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
FUMBX Fidelity Short-Term Treasury Bond Index Fund	0.15%	5.83%	3.25%	4.47%	-5.84%	-1.38%	4.22%	4.19%	1.47%	-0.33%
ISTB iShares Core 1-5 Year USD Bond ETF	0.63%	6.36%	4.37%	5.56%	-6.08%	-0.71%	4.75%	5.61%	1.02%	-0.15%

Correlation

The correlation between FUMBX and ISTB is 0.83, meaning they have usually moved in the same direction, including during past declines.

	Correlation
Correlation (1Y) Focuses on recent behavior, but can change the most.	0.83
Correlation (3Y) Balances recent behavior with more history.	0.86
Correlation (5Y) Shows whether the relationship held over a longer period.	0.88
Correlation (All Time) Calculated using the full available price history since Oct 19, 2017	0.78

The correlation between FUMBX and ISTB shifts across timeframes, from 0.78 (all time) to 0.88 (5 years), reflecting how their relationship changes across market environments.

Return for Risk

FUMBX vs. ISTB — Risk / Return Rank

Compare historical risk-adjusted metric ranks over the past 12 months.

FUMBX

FUMBX Risk / Return Rank: 55
FUMBX Sharpe Ratio Rank: 57
FUMBX Sortino Ratio Rank: 64
FUMBX Omega Ratio Rank: 66
FUMBX Calmar Ratio Rank: 52
FUMBX Martin Ratio Rank: 35

ISTB

ISTB Risk / Return Rank: 79
ISTB Sharpe Ratio Rank: 80
ISTB Sortino Ratio Rank: 84
ISTB Omega Ratio Rank: 82
ISTB Calmar Ratio Rank: 75
ISTB Martin Ratio Rank: 75

The rank (0–100) uses a weighted average of the Sharpe, Sortino, Omega, Calmar, and Martin percentile ranks for the trailing 12 months. Higher means stronger historical risk-adjusted performance within the peer group.

FUMBX vs. ISTB - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Short-Term Treasury Bond Index Fund (FUMBX) and iShares Core 1-5 Year USD Bond ETF (ISTB). 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.

	FUMBX	ISTB	Difference
Sharpe ratio: Return per unit of total volatility	1.38	1.83	-0.44
Sortino ratio: Return per unit of downside risk	2.14	2.77	-0.63
Omega ratio: Gain probability vs. loss probability	1.28	1.34	-0.06
Calmar ratio: Return relative to maximum drawdown	1.84	2.61	-0.77
Martin ratio: Return relative to average drawdown	4.96	9.39	-4.43

FUMBX vs. ISTB - Sharpe Ratio Comparison

The current FUMBX Sharpe Ratio is 1.38, which is comparable to the ISTB Sharpe Ratio of 1.83. The chart below compares the historical Sharpe Ratios of FUMBX and ISTB, 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

FUMBX vs. ISTB - Drawdown Comparison

The maximum FUMBX drawdown since its inception was -8.83%, smaller than the maximum ISTB drawdown of -9.34%. Use the drawdown chart below to compare losses from any high point for FUMBX and ISTB.

Drawdown Indicators

	FUMBX	ISTB	Difference
Max Drawdown Largest peak-to-trough decline	-8.83%	-9.34%	+0.51%
Max Drawdown (1Y) Largest decline over 1 year	-1.54%	-1.26%	-0.28%
Max Drawdown (3Y) Largest decline over 3 years	-1.57%	-1.36%	-0.21%
Max Drawdown (5Y) Largest decline over 5 years	-8.51%	-9.33%	+0.82%
Max Drawdown (10Y) Largest decline over 10 years	—	-9.34%	—
Current Drawdown Current decline from peak	-0.81%	-0.27%	-0.54%
Average Drawdown Average peak-to-trough decline	-1.84%	-1.21%	-0.63%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.57%	0.35%	+0.22%

Volatility

FUMBX vs. ISTB - Volatility Comparison

Fidelity Short-Term Treasury Bond Index Fund (FUMBX) has a higher volatility of 0.53% compared to iShares Core 1-5 Year USD Bond ETF (ISTB) at 0.48%. This indicates that FUMBX's price experiences larger fluctuations and is considered to be riskier than ISTB based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FUMBX	ISTB	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.53%	0.48%	+0.05%
Volatility (6M) Calculated over the trailing 6-month period	1.62%	1.42%	+0.20%
Volatility (1Y) Calculated over the trailing 1-year period	2.05%	1.80%	+0.25%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	2.93%	2.81%	+0.12%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	2.48%	2.51%	-0.03%

FUMBX vs. ISTB - Expense Ratio Comparison

FUMBX has a 0.03% expense ratio, which is lower than ISTB's 0.06% expense ratio. Despite the difference, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

FUMBX vs. ISTB - Dividend Comparison

FUMBX's dividend yield for the trailing twelve months is around 3.56%, less than ISTB's 4.26% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FUMBX Fidelity Short-Term Treasury Bond Index Fund	3.56%	3.51%	2.91%	1.64%	0.86%	1.15%	1.41%	1.88%	1.64%	0.34%	0.00%	0.00%
ISTB iShares Core 1-5 Year USD Bond ETF	3.91%	4.12%	3.83%	2.97%	2.01%	1.69%	2.20%	2.75%	2.57%	2.06%	1.90%	1.58%

Frequently Asked Questions

Can I hold both FUMBX and ISTB in my portfolio?

FUMBX and ISTB have a correlation of 0.83, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, FUMBX or ISTB?

FUMBX has higher volatility (0.53%) compared to ISTB (0.48%). In terms of maximum drawdown, FUMBX dropped -8.83% vs ISTB's -9.34%.

Which has better risk-adjusted returns?

ISTB currently has the higher Sharpe Ratio (1.83 vs 1.38), 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.