RBFFX vs. WFBIX
RBFFX (American Funds The Bond Fund of America) and WFBIX (iShares U.S. Aggregate Bond Index Fund) are both Intermediate Core Bond funds. Over the past 10 years, RBFFX returned 2.01%/yr vs 1.96%/yr for WFBIX. Their correlation of 0.89 suggests significant overlap in exposure. RBFFX charges 0.29%/yr vs 0.05%/yr for WFBIX.
Performance
RBFFX vs. WFBIX - Performance Comparison
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Returns By Period
In the year-to-date period, RBFFX achieves a 0.22% return, which is significantly lower than WFBIX's 0.43% return. Both investments have delivered pretty close results over the past 10 years, with RBFFX having a 2.01% annualized return and WFBIX not far behind at 1.96%.
RBFFX
- 1D
- 0.00%
- 1M
- 0.47%
- YTD
- 0.22%
- 6M
- 0.16%
- 1Y
- 5.34%
- 3Y*
- 3.98%
- 5Y*
- 0.16%
- 10Y*
- 2.01%
WFBIX
- 1D
- 0.00%
- 1M
- 0.45%
- YTD
- 0.43%
- 6M
- 0.32%
- 1Y
- 5.35%
- 3Y*
- 5.33%
- 5Y*
- 0.99%
- 10Y*
- 1.96%
RBFFX vs. WFBIX - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
RBFFX American Funds The Bond Fund of America | 0.22% | 7.49% | 1.47% | 4.65% | -13.03% | -0.64% | 11.07% | 8.13% | 0.17% | 3.53% |
WFBIX iShares U.S. Aggregate Bond Index Fund | 0.43% | 7.16% | 1.43% | 9.65% | -13.03% | -1.79% | 7.40% | 8.72% | -0.08% | 3.39% |
Correlation
The correlation between RBFFX and WFBIX is 0.96 - these two move nearly in lockstep. At this level, holding both provides almost no diversification benefit. If you already own one, adding the other does little to reduce portfolio risk.
| Correlation | |
|---|---|
Correlation (1Y) Calculated over the trailing 1-year period | 0.96 |
Correlation (3Y) Calculated over the trailing 3-year period | 0.95 |
Correlation (5Y) Calculated over the trailing 5-year period | 0.96 |
Correlation (10Y) Calculated over the trailing 10-year period | 0.93 |
Correlation (All Time) Calculated using the full available price history since Jan 3, 2003 | 0.89 |
The correlation between RBFFX and WFBIX has been stable across timeframes, ranging from 0.89 to 0.96 - a consistent structural relationship.
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Return for Risk
RBFFX vs. WFBIX — Risk / Return Rank
RBFFX
WFBIX
RBFFX vs. WFBIX - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for American Funds The Bond Fund of America (RBFFX) and iShares U.S. Aggregate Bond Index Fund (WFBIX). 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.
| RBFFX | WFBIX | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | 0.00 | ||
| Sortino ratioReturn per unit of downside risk | +0.02 | ||
| Omega ratioGain probability vs. loss probability | 1.24 | 1.25 | 0.00 |
| Calmar ratioReturn relative to maximum drawdown | 1.74 | 1.78 | -0.04 |
| Martin ratioReturn relative to average drawdown | 5.20 | 5.34 | -0.13 |
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month. | |||
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Sharpe Ratios by Period
| RBFFX | WFBIX | Difference | |
|---|---|---|---|
Sharpe Ratio (1Y)Calculated over the trailing 1-year period | 1.36 | 1.36 | 0.00 |
Sharpe Ratio (5Y)Calculated over the trailing 5-year period | 0.03 | 0.16 | -0.13 |
Sharpe Ratio (10Y)Calculated over the trailing 10-year period | 0.41 | 0.38 | +0.03 |
Sharpe Ratio (All Time)Calculated using the full available price history | 0.82 | 0.94 | -0.13 |
Drawdowns
RBFFX vs. WFBIX - Drawdown Comparison
The maximum RBFFX drawdown since its inception was -17.62%, smaller than the maximum WFBIX drawdown of -18.68%. Use the drawdown chart below to compare losses from any high point for RBFFX and WFBIX.
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Drawdown Indicators
| RBFFX | WFBIX | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -17.62% | -18.68% | +1.06% |
Max Drawdown (1Y)Largest decline over 1 year | -3.09% | -3.02% | -0.07% |
Max Drawdown (3Y)Largest decline over 3 years | -6.11% | -6.09% | -0.02% |
Max Drawdown (5Y)Largest decline over 5 years | -17.62% | -17.84% | +0.22% |
Max Drawdown (10Y)Largest decline over 10 years | -17.62% | -18.68% | +1.06% |
Current DrawdownCurrent decline from peak | -1.50% | -1.50% | 0.00% |
Average DrawdownAverage peak-to-trough decline | -2.81% | -2.26% | -0.55% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 1.03% | 1.00% | +0.03% |
Volatility
RBFFX vs. WFBIX - Volatility Comparison
American Funds The Bond Fund of America (RBFFX) and iShares U.S. Aggregate Bond Index Fund (WFBIX) have volatilities of 1.40% and 1.34%, respectively, indicating that both stocks experience similar levels of price fluctuations. This suggests that the risk associated with both stocks, as measured by volatility, is nearly the same. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| RBFFX | WFBIX | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 1.40% | 1.34% | +0.06% |
Volatility (6M)Calculated over the trailing 6-month period | 2.84% | 2.83% | +0.01% |
Volatility (1Y)Calculated over the trailing 1-year period | 3.96% | 3.97% | -0.01% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 5.97% | 6.40% | -0.43% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 4.90% | 5.17% | -0.27% |
RBFFX vs. WFBIX - Expense Ratio Comparison
RBFFX has a 0.29% expense ratio, which is higher than WFBIX's 0.05% expense ratio.
Dividends
RBFFX vs. WFBIX - Dividend Comparison
RBFFX's dividend yield for the trailing twelve months is around 4.45%, more than WFBIX's 3.91% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
RBFFX American Funds The Bond Fund of America | 4.45% | 4.43% | 4.61% | 3.53% | 2.42% | 2.31% | 5.34% | 3.76% | 2.67% | 2.14% | 2.07% | 2.30% |
WFBIX iShares U.S. Aggregate Bond Index Fund | 3.91% | 3.78% | 3.68% | 6.82% | 2.60% | 2.04% | 2.43% | 2.88% | 2.71% | 2.24% | 2.25% | 2.20% |
Frequently Asked Questions
With a correlation of 0.96, RBFFX and WFBIX move almost identically. Holding both adds very little diversification - you're essentially doubling your position in the same market segment. Choosing one is usually more capital-efficient.
RBFFX has higher volatility (1.40%) compared to WFBIX (1.34%). In terms of maximum drawdown, RBFFX dropped -17.62% vs WFBIX's -18.68%.
RBFFX currently has the higher Sharpe Ratio (1.36 vs 1.36), 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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