SDSI vs. FLDB

Last updated Jun 5, 2026

SDSI (American Century Short Duration Strategic Income ETF) and FLDB (Fidelity Low Duration Bond ETF) are both Short-Term Bond funds. SDSI is passively managed, while FLDB is actively managed. Over the past year, SDSI returned 4.64% vs 4.20% for FLDB. At a 0.26 correlation, their price movements are largely independent. SDSI charges 0.33%/yr vs 0.20%/yr for FLDB.

Performance

SDSI vs. FLDB - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Century Short Duration Strategic Income ETF (SDSI) and Fidelity Low Duration Bond ETF (FLDB). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, SDSI achieves a 0.90% return, which is significantly lower than FLDB's 1.36% return.

SDSI

• 1D: -0.32%
• 1M: -0.03%
• YTD: 0.90%
• 6M: 1.36%
• 1Y: 4.64%
• 3Y*: 5.66%
• 5Y*: —
• 10Y*: —

FLDB

• 1D: 0.08%
• 1M: 0.31%
• YTD: 1.36%
• 6M: 1.82%
• 1Y: 4.20%
• 3Y*: —
• 5Y*: —
• 10Y*: —

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

SDSI vs. FLDB - Yearly Performance Comparison

	2026 (YTD)	2025	2024
SDSI American Century Short Duration Strategic Income ETF	0.90%	6.54%	5.35%
FLDB Fidelity Low Duration Bond ETF	1.36%	4.93%	4.29%

Correlation

The correlation between SDSI and FLDB is 0.34, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.34
Correlation (All Time) Calculated using the full available price history since Feb 27, 2024	0.26

Return for Risk

SDSI vs. FLDB — Risk / Return Rank

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

SDSI

SDSI Risk / Return Rank: 87
SDSI Sharpe Ratio Rank: 87
SDSI Sortino Ratio Rank: 91
SDSI Omega Ratio Rank: 89
SDSI Calmar Ratio Rank: 79
SDSI Martin Ratio Rank: 88

FLDB

FLDB Risk / Return Rank: 98
FLDB Sharpe Ratio Rank: 97
FLDB Sortino Ratio Rank: 98
FLDB Omega Ratio Rank: 98
FLDB Calmar Ratio Rank: 99
FLDB 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.

SDSI vs. FLDB - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Century Short Duration Strategic Income ETF (SDSI) and Fidelity Low Duration Bond ETF (FLDB). 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.

	SDSI	FLDB	Difference
Sharpe ratio: Return per unit of total volatility	2.83	4.68	-1.85
Sortino ratio: Return per unit of downside risk	4.22	8.45	-4.23
Omega ratio: Gain probability vs. loss probability	1.56	2.11	-0.55
Calmar ratio: Return relative to maximum drawdown	3.98	25.15	-21.17
Martin ratio: Return relative to average drawdown	18.71	93.64	-74.93
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

SDSI vs. FLDB - Sharpe Ratio Comparison

The current SDSI Sharpe Ratio is 2.83, which is lower than the FLDB Sharpe Ratio of 4.68. The chart below compares the historical Sharpe Ratios of SDSI and FLDB, 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

	SDSI	FLDB	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.83	4.68	-1.85
Sharpe Ratio (All Time) Calculated using the full available price history	2.55	3.59	-1.04

Drawdowns

SDSI vs. FLDB - Drawdown Comparison

The maximum SDSI drawdown since its inception was -1.29%, which is greater than FLDB's maximum drawdown of -0.49%. Use the drawdown chart below to compare losses from any high point for SDSI and FLDB.

Drawdown Indicators

	SDSI	FLDB	Difference
Max Drawdown Largest peak-to-trough decline	-1.29%	-0.49%	-0.80%
Max Drawdown (1Y) Largest decline over 1 year	-1.17%	-0.17%	-1.00%
Max Drawdown (3Y) Largest decline over 3 years	-1.29%	—	—
Current Drawdown Current decline from peak	-0.39%	-0.05%	-0.34%
Average Drawdown Average peak-to-trough decline	-0.24%	-0.05%	-0.19%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.25%	0.04%	+0.21%

Volatility

SDSI vs. FLDB - Volatility Comparison

American Century Short Duration Strategic Income ETF (SDSI) has a higher volatility of 0.52% compared to Fidelity Low Duration Bond ETF (FLDB) at 0.34%. This indicates that SDSI's price experiences larger fluctuations and is considered to be riskier than FLDB based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	SDSI	FLDB	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.52%	0.34%	+0.18%
Volatility (6M) Calculated over the trailing 6-month period	1.18%	0.62%	+0.56%
Volatility (1Y) Calculated over the trailing 1-year period	1.67%	0.90%	+0.77%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	2.28%	1.31%	+0.97%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	2.28%	1.31%	+0.97%

SDSI vs. FLDB - Expense Ratio Comparison

SDSI has a 0.33% expense ratio, which is higher than FLDB's 0.20% expense ratio.

Dividends

SDSI vs. FLDB - Dividend Comparison

SDSI's dividend yield for the trailing twelve months is around 4.43%, which matches FLDB's 4.45% yield.

Position	TTM	2025	2024	2023	2022
FLDB Fidelity Low Duration Bond ETF	4.45%	4.72%	3.58%	0.00%	0.00%
SDSI American Century Short Duration Strategic Income ETF	4.43%	4.91%	5.49%	5.37%	0.98%

Frequently Asked Questions

Can I hold both SDSI and FLDB in my portfolio?

SDSI and FLDB have a correlation of 0.34, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, SDSI or FLDB?

SDSI has higher volatility (0.52%) compared to FLDB (0.34%). In terms of maximum drawdown, SDSI dropped -1.29% vs FLDB's -0.49%.

Which ETF is better, SDSI or FLDB?

On 1-year performance, SDSI leads with 4.64% vs 4.20% for FLDB. On fees, FLDB is cheaper at 0.20% per year. On volatility, FLDB has been the lower-risk option at 0.34%. The better choice depends on whether you care most about return, fees, risk, or income.

Which ETF has performed better, SDSI or FLDB?

Over the 1-year period, SDSI has performed better with a 4.64% return vs 4.20%. Past performance does not guarantee future results, so compare this with risk, fees, and fund exposure.

Which ETF is cheaper, SDSI or FLDB?

FLDB is cheaper with a 0.20% expense ratio, compared with 0.33% for SDSI.

Which ETF pays a higher dividend yield, SDSI or FLDB?

FLDB has the higher dividend yield at 4.45%, compared with 4.43% for SDSI.

What is the main difference between SDSI and FLDB?

They also come from different issuers: American Century and Fidelity. Their fees differ too: 0.33% for SDSI and 0.20% for FLDB.

Which has better risk-adjusted returns?

FLDB currently has the higher Sharpe Ratio (4.68 vs 2.83), 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.