BFMCX vs. WFBIX

Last updated Jun 3, 2026

BFMCX (BlackRock Core Bond Portfolio) and WFBIX (iShares U.S. Aggregate Bond Index Fund) are both Intermediate Core Bond funds from BlackRock. Over the past 10 years, BFMCX returned 1.56%/yr vs 1.96%/yr for WFBIX. Their correlation of 0.89 suggests significant overlap in exposure. BFMCX charges 0.44%/yr vs 0.05%/yr for WFBIX.

Performance

BFMCX vs. WFBIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in BlackRock Core Bond Portfolio (BFMCX) and iShares U.S. Aggregate Bond Index Fund (WFBIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, BFMCX achieves a 0.31% return, which is significantly lower than WFBIX's 0.43% return. Over the past 10 years, BFMCX has underperformed WFBIX with an annualized return of 1.56%, while WFBIX has yielded a comparatively higher 1.96% annualized return.

BFMCX

• 1D: 0.00%
• 1M: 0.22%
• YTD: 0.31%
• 6M: 0.43%
• 1Y: 5.43%
• 3Y*: 3.53%
• 5Y*: -0.30%
• 10Y*: 1.56%

WFBIX

• 1D: -0.11%
• 1M: 0.11%
• YTD: 0.43%
• 6M: 0.43%
• 1Y: 5.35%
• 3Y*: 5.33%
• 5Y*: 0.95%
• 10Y*: 1.96%

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

BFMCX vs. WFBIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
BFMCX BlackRock Core Bond Portfolio	0.31%	7.43%	0.66%	5.32%	-14.35%	-1.52%	8.32%	9.85%	-0.28%	3.16%
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 BFMCX and WFBIX is 0.95 - 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	0.96
Correlation (5Y) Calculated over the trailing 5-year period	0.96
Correlation (10Y) Calculated over the trailing 10-year period	0.94
Correlation (All Time) Calculated using the full available price history since Jul 6, 1993	0.89

The correlation between BFMCX and WFBIX has been stable across timeframes, ranging from 0.89 to 0.96 - a consistent structural relationship.

Return for Risk

BFMCX vs. WFBIX — Risk / Return Rank

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

BFMCX

BFMCX Risk / Return Rank: 19
BFMCX Sharpe Ratio Rank: 19
BFMCX Sortino Ratio Rank: 19
BFMCX Omega Ratio Rank: 18
BFMCX Calmar Ratio Rank: 22
BFMCX Martin Ratio Rank: 18

WFBIX

WFBIX Risk / Return Rank: 20
WFBIX Sharpe Ratio Rank: 18
WFBIX Sortino Ratio Rank: 19
WFBIX Omega Ratio Rank: 18
WFBIX Calmar Ratio Rank: 23
WFBIX Martin Ratio Rank: 20

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.

BFMCX vs. WFBIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for BlackRock Core Bond Portfolio (BFMCX) 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.

	BFMCX	WFBIX	Difference
Sharpe ratio Return per unit of total volatility	1.28	1.26	+0.01
Sortino ratio Return per unit of downside risk	1.87	1.89	-0.02
Omega ratio Gain probability vs. loss probability	1.23	1.23	0.00
Calmar ratio Return relative to maximum drawdown	1.77	1.85	-0.08
Martin ratio Return relative to average drawdown	5.21	5.57	-0.36
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

BFMCX vs. WFBIX - Sharpe Ratio Comparison

The current BFMCX Sharpe Ratio is 1.28, which is comparable to the WFBIX Sharpe Ratio of 1.26. The chart below compares the historical Sharpe Ratios of BFMCX and WFBIX, 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

	BFMCX	WFBIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.28	1.26	+0.01
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	-0.05	0.15	-0.20
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.31	0.38	-0.07
Sharpe Ratio (All Time) Calculated using the full available price history	0.87	0.94	-0.07

Drawdowns

BFMCX vs. WFBIX - Drawdown Comparison

The maximum BFMCX drawdown since its inception was -19.49%, roughly equal to the maximum WFBIX drawdown of -18.68%. Use the drawdown chart below to compare losses from any high point for BFMCX and WFBIX.

Drawdown Indicators

	BFMCX	WFBIX	Difference
Max Drawdown Largest peak-to-trough decline	-19.49%	-18.68%	-0.81%
Max Drawdown (1Y) Largest decline over 1 year	-3.25%	-3.02%	-0.23%
Max Drawdown (3Y) Largest decline over 3 years	-6.76%	-6.09%	-0.67%
Max Drawdown (5Y) Largest decline over 5 years	-19.32%	-17.84%	-1.48%
Max Drawdown (10Y) Largest decline over 10 years	-19.49%	-18.68%	-0.81%
Current Drawdown Current decline from peak	-3.64%	-1.50%	-2.14%
Average Drawdown Average peak-to-trough decline	-2.73%	-2.26%	-0.47%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.10%	1.00%	+0.10%

Volatility

BFMCX vs. WFBIX - Volatility Comparison

BlackRock Core Bond Portfolio (BFMCX) has a higher volatility of 1.42% compared to iShares U.S. Aggregate Bond Index Fund (WFBIX) at 1.34%. This indicates that BFMCX's price experiences larger fluctuations and is considered to be riskier than WFBIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	BFMCX	WFBIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.42%	1.34%	+0.08%
Volatility (6M) Calculated over the trailing 6-month period	3.06%	2.84%	+0.22%
Volatility (1Y) Calculated over the trailing 1-year period	4.08%	3.98%	+0.10%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.14%	6.40%	-0.26%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	5.05%	5.17%	-0.12%

BFMCX vs. WFBIX - Expense Ratio Comparison

BFMCX has a 0.44% expense ratio, which is higher than WFBIX's 0.05% expense ratio.

Dividends

BFMCX vs. WFBIX - Dividend Comparison

BFMCX's dividend yield for the trailing twelve months is around 4.36%, more than WFBIX's 3.91% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
BFMCX BlackRock Core Bond Portfolio	4.36%	4.10%	3.86%	3.21%	1.86%	2.11%	5.78%	2.86%	3.02%	2.69%	2.41%	2.57%
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

Can I hold both BFMCX and WFBIX in my portfolio?

With a correlation of 0.95, BFMCX 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.

Which is riskier, BFMCX or WFBIX?

BFMCX has higher volatility (1.42%) compared to WFBIX (1.34%). In terms of maximum drawdown, BFMCX dropped -19.49% vs WFBIX's -18.68%.

Which has better risk-adjusted returns?

BFMCX currently has the higher Sharpe Ratio (1.28 vs 1.26), 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.