MFAAX vs. FNBGX
MFAAX (American Funds Mortgage Fund) and FNBGX (Fidelity Long-Term Treasury Bond Index Fund) are both Government Bonds funds. Over the past 5 years, MFAAX returned -0.27%/yr vs -7.27%/yr for FNBGX. Their 0.77 correlation means they have sometimes moved together and sometimes differently. MFAAX charges 0.64%/yr vs 0.03%/yr for FNBGX.
Performance
MFAAX vs. FNBGX - Performance Comparison
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Returns By Period
In the year-to-date period, MFAAX achieves a -1.18% return, which is significantly higher than FNBGX's -3.60% return.
MFAAX
- 1D
- -0.12%
- 1M
- -1.14%
- 6M
- -1.29%
- YTD
- -1.18%
- 1Y
- 1.69%
- 3Y*
- 3.39%
- 5Y*
- -0.27%
- 10Y*
- 1.06%
- ALL TIME*
- 1.61%
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%
Liquidity Comparison
| Position | Avg. Volume Value (2W) | Avg. Volume Value (1M) | Avg. Volume Value (3M) |
|---|---|---|---|
| $0.00 | $0.00 | $0.00 | |
| $0.00 | $0.00 | $0.00 |
MFAAX vs. FNBGX - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
MFAAX American Funds Mortgage Fund | -1.18% | 8.46% | 0.55% | 2.87% | -10.52% | -0.64% | 6.59% | 4.70% | 0.49% | -0.35% |
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 MFAAX and FNBGX is 0.81, 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. | 0.81 |
Correlation (3Y) Balances recent behavior with more history. | 0.85 |
Correlation (5Y) Shows whether the relationship held over a longer period. | 0.84 |
Correlation (All Time) Calculated using the full available price history since Oct 19, 2017 | 0.77 |
The correlation between MFAAX and FNBGX has been stable across timeframes, ranging from 0.77 to 0.85 - a consistent structural relationship.
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Return for Risk
MFAAX vs. FNBGX — Risk / Return Rank
MFAAX
FNBGX
MFAAX vs. FNBGX - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for American Funds Mortgage Fund (MFAAX) 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.
| MFAAX | FNBGX | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | +0.90 | ||
| Sortino ratioReturn per unit of downside risk | +1.31 | ||
| Omega ratioGain probability vs. loss probability | 1.15 | 0.99 | +0.15 |
| Calmar ratioReturn relative to maximum drawdown | 0.98 | -0.10 | +1.08 |
| Martin ratioReturn relative to average drawdown | 2.52 | -0.23 | +2.74 |
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Drawdowns
MFAAX vs. FNBGX - Drawdown Comparison
The maximum MFAAX drawdown since its inception was -16.60%, smaller than the maximum FNBGX drawdown of -46.86%. Use the drawdown chart below to compare losses from any high point for MFAAX and FNBGX.
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Drawdown Indicators
| MFAAX | FNBGX | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -16.60% | -46.86% | +30.26% |
Max Drawdown (1Y)Largest decline over 1 year | -3.33% | -7.38% | +4.05% |
Max Drawdown (3Y)Largest decline over 3 years | -6.25% | -13.48% | +7.23% |
Max Drawdown (5Y)Largest decline over 5 years | -16.60% | -41.54% | +24.94% |
Max Drawdown (10Y)Largest decline over 10 years | -16.60% | — | — |
Current DrawdownCurrent decline from peak | -2.70% | -39.51% | +36.81% |
Average DrawdownAverage peak-to-trough decline | -2.62% | -21.94% | +19.32% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 1.29% | 3.29% | -2.00% |
Volatility
MFAAX vs. FNBGX - Volatility Comparison
The current volatility for American Funds Mortgage Fund (MFAAX) is 1.07%, while Fidelity Long-Term Treasury Bond Index Fund (FNBGX) has a volatility of 2.25%. This indicates that MFAAX 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.
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Volatility by Period
| MFAAX | FNBGX | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 1.07% | 2.25% | -1.18% |
Volatility (6M)Calculated over the trailing 6-month period | 3.20% | 6.37% | -3.17% |
Volatility (1Y)Calculated over the trailing 1-year period | 4.01% | 8.46% | -4.45% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 6.43% | 14.46% | -8.03% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 4.85% | 14.11% | -9.26% |
MFAAX vs. FNBGX - Expense Ratio Comparison
MFAAX has a 0.64% expense ratio, which is higher than FNBGX's 0.03% expense ratio.
Dividends
MFAAX vs. FNBGX - Dividend Comparison
MFAAX's dividend yield for the trailing twelve months is around 3.82%, which matches 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% |
MFAAX American Funds Mortgage Fund | 3.82% | 4.18% | 4.49% | 3.24% | 1.36% | 0.33% | 4.38% | 2.90% | 1.77% | 1.65% | 2.34% | 2.44% |
Frequently Asked Questions
MFAAX and FNBGX have a correlation of 0.81, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.
FNBGX has higher volatility (2.25%) compared to MFAAX (1.07%). In terms of maximum drawdown, MFAAX dropped -16.60% vs FNBGX's -46.86%.
MFAAX currently has the higher Sharpe Ratio (0.81 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.
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