TWUSX vs. FNBGX

Last updated Aug 4, 2026

TWUSX (American Century Short-Term Government Fund) and FNBGX (Fidelity Long-Term Treasury Bond Index Fund) are both Government Bonds funds. Over the past 5 years, TWUSX returned 1.45%/yr vs -7.27%/yr for FNBGX. Their 0.52 correlation means they have sometimes moved together and sometimes differently. TWUSX charges 0.55%/yr vs 0.03%/yr for FNBGX.

Performance

TWUSX vs. FNBGX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in American Century Short-Term Government Fund (TWUSX) and Fidelity Long-Term Treasury Bond Index Fund (FNBGX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, TWUSX achieves a 0.22% return, which is significantly higher than FNBGX's -3.60% return.

TWUSX

• 1D: -0.11%
• 1M: -0.33%
• 6M: 0.15%
• YTD: 0.22%
• 1Y: 1.96%
• 3Y*: 3.94%
• 5Y*: 1.45%
• 10Y*: 1.48%
• ALL TIME*: -2.30%

FNBGX

• 1D: -0.68%
• 1M: -3.83%
• 6M: -3.19%
• YTD: -3.60%
• 1Y: -2.02%
• 3Y*: -0.74%
• 5Y*: -7.27%
• 10Y*: —
• ALL TIME*: -1.45%

*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)
FNBGX Fidelity Long-Term Treasury Bond Index Fund	$0.00	$0.00	$0.00
TWUSX American Century Short-Term Government Fund	$0.00	$0.00	$0.00

TWUSX vs. FNBGX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
TWUSX American Century Short-Term Government Fund	0.22%	4.94%	3.59%	3.70%	-4.31%	-0.09%	3.36%	2.91%	1.12%	-0.09%
FNBGX Fidelity Long-Term Treasury Bond Index Fund	-3.60%	5.30%	-6.18%	3.20%	-29.89%	-5.17%	17.58%	14.24%	-1.62%	1.86%

Correlation

The correlation between TWUSX and FNBGX is 0.55, which is moderate. They have sometimes moved together and sometimes differently, sharing some price drivers without tracking each other closely.

	Correlation
Correlation (1Y) Focuses on recent behavior, but can change the most.	0.55
Correlation (3Y) Balances recent behavior with more history.	0.57
Correlation (5Y) Shows whether the relationship held over a longer period.	0.56
Correlation (All Time) Calculated using the full available price history since Oct 19, 2017	0.52

The correlation between TWUSX and FNBGX has been stable across timeframes, ranging from 0.52 to 0.57 - a consistent structural relationship.

Return for Risk

TWUSX vs. FNBGX — Risk / Return Rank

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

TWUSX

TWUSX Risk / Return Rank: 59
TWUSX Sharpe Ratio Rank: 44
TWUSX Sortino Ratio Rank: 65
TWUSX Omega Ratio Rank: 61
TWUSX Calmar Ratio Rank: 71
TWUSX Martin Ratio Rank: 56

FNBGX

FNBGX Risk / Return Rank: 3
FNBGX Sharpe Ratio Rank: 3
FNBGX Sortino Ratio Rank: 3
FNBGX Omega Ratio Rank: 3
FNBGX Calmar Ratio Rank: 3
FNBGX Martin Ratio Rank: 3

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.

TWUSX vs. FNBGX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for American Century Short-Term Government Fund (TWUSX) and Fidelity Long-Term Treasury Bond Index Fund (FNBGX). 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.

	TWUSX	FNBGX	Difference
Sharpe ratio: Return per unit of total volatility	1.39	-0.09	+1.48
Sortino ratio: Return per unit of downside risk	2.38	-0.06	+2.44
Omega ratio: Gain probability vs. loss probability	1.30	0.99	+0.31
Calmar ratio: Return relative to maximum drawdown	2.47	-0.10	+2.57
Martin ratio: Return relative to average drawdown	7.99	-0.23	+8.21

TWUSX vs. FNBGX - Sharpe Ratio Comparison

The current TWUSX Sharpe Ratio is 1.39, which is higher than the FNBGX Sharpe Ratio of -0.09. The chart below compares the historical Sharpe Ratios of TWUSX and FNBGX, 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

TWUSX vs. FNBGX - Drawdown Comparison

The maximum TWUSX drawdown since its inception was -91.06%, which is greater than FNBGX's maximum drawdown of -46.86%. Use the drawdown chart below to compare losses from any high point for TWUSX and FNBGX.

Drawdown Indicators

	TWUSX	FNBGX	Difference
Max Drawdown Largest peak-to-trough decline	-91.06%	-46.86%	-44.20%
Max Drawdown (1Y) Largest decline over 1 year	-0.98%	-7.38%	+6.40%
Max Drawdown (3Y) Largest decline over 3 years	-1.09%	-13.48%	+12.39%
Max Drawdown (5Y) Largest decline over 5 years	-5.76%	-41.54%	+35.78%
Max Drawdown (10Y) Largest decline over 10 years	-5.85%	—	—
Current Drawdown Current decline from peak	-64.67%	-39.51%	-25.16%
Average Drawdown Average peak-to-trough decline	-76.88%	-21.94%	-54.94%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.30%	3.29%	-2.99%

Volatility

TWUSX vs. FNBGX - Volatility Comparison

The current volatility for American Century Short-Term Government Fund (TWUSX) is 0.37%, while Fidelity Long-Term Treasury Bond Index Fund (FNBGX) has a volatility of 2.25%. This indicates that TWUSX experiences smaller price fluctuations and is considered to be less risky than FNBGX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	TWUSX	FNBGX	Difference
Volatility (1M) Calculated over the trailing 1-month period	0.37%	2.25%	-1.88%
Volatility (6M) Calculated over the trailing 6-month period	1.31%	6.37%	-5.06%
Volatility (1Y) Calculated over the trailing 1-year period	1.76%	8.46%	-6.70%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	2.32%	14.46%	-12.14%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	1.82%	14.11%	-12.29%

TWUSX vs. FNBGX - Expense Ratio Comparison

TWUSX has a 0.55% expense ratio, which is higher than FNBGX's 0.03% expense ratio.

Dividends

TWUSX vs. FNBGX - Dividend Comparison

TWUSX's dividend yield for the trailing twelve months is around 3.29%, less than FNBGX's 3.82% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FNBGX Fidelity Long-Term Treasury Bond Index Fund	3.82%	3.88%	3.75%	3.20%	2.26%	2.47%	3.96%	2.63%	2.93%	0.70%	0.00%	0.00%
TWUSX American Century Short-Term Government Fund	3.29%	3.70%	4.06%	3.83%	1.12%	1.05%	0.72%	1.81%	1.74%	1.06%	0.57%	0.53%

Frequently Asked Questions

Can I hold both TWUSX and FNBGX in my portfolio?

TWUSX and FNBGX have a correlation of 0.55, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, TWUSX or FNBGX?

FNBGX has higher volatility (2.25%) compared to TWUSX (0.37%). In terms of maximum drawdown, TWUSX dropped -91.06% vs FNBGX's -46.86%.

Which has better risk-adjusted returns?

TWUSX currently has the higher Sharpe Ratio (1.39 vs -0.09), 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.