VMBSX vs. FEPAX

Last updated Jun 5, 2026

VMBSX (Vanguard Mortgage-Backed Securities Index Fund Admiral Shares) and FEPAX (Fidelity Advisor Total Bond Fund Class A) are both Total Bond Market funds. Over the past 10 years, VMBSX returned 1.85%/yr vs 2.04%/yr for FEPAX. Their correlation of 0.82 suggests significant overlap in exposure. VMBSX charges 0.07%/yr vs 0.75%/yr for FEPAX.

Performance

VMBSX vs. FEPAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard Mortgage-Backed Securities Index Fund Admiral Shares (VMBSX) and Fidelity Advisor Total Bond Fund Class A (FEPAX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, VMBSX achieves a 0.60% return, which is significantly higher than FEPAX's 0.24% return. Over the past 10 years, VMBSX has underperformed FEPAX with an annualized return of 1.85%, while FEPAX has yielded a comparatively higher 2.04% annualized return.

VMBSX

• 1D: -0.21%
• 1M: 0.08%
• YTD: 0.60%
• 6M: 0.94%
• 1Y: 6.11%
• 3Y*: 4.62%
• 5Y*: 0.47%
• 10Y*: 1.85%

FEPAX

• 1D: -0.21%
• 1M: 0.13%
• YTD: 0.24%
• 6M: 0.36%
• 1Y: 4.66%
• 3Y*: 4.13%
• 5Y*: 0.16%
• 10Y*: 2.04%

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

VMBSX vs. FEPAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VMBSX Vanguard Mortgage-Backed Securities Index Fund Admiral Shares	0.60%	8.43%	1.76%	4.99%	-11.56%	-1.35%	3.74%	11.47%	0.87%	2.32%
FEPAX Fidelity Advisor Total Bond Fund Class A	0.24%	7.18%	1.16%	6.54%	-13.76%	-0.56%	9.02%	9.55%	-1.07%	3.79%

Correlation

The correlation between VMBSX and FEPAX is 0.90, indicating a strong positive relationship between their price movements. Combining them offers limited diversification - they tend to fall together during downturns.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.90
Correlation (3Y) Calculated over the trailing 3-year period	0.92
Correlation (5Y) Calculated over the trailing 5-year period	0.91
Correlation (10Y) Calculated over the trailing 10-year period	0.85
Correlation (All Time) Calculated using the full available price history since Nov 24, 2009	0.82

The correlation between VMBSX and FEPAX has been stable across timeframes, ranging from 0.82 to 0.92 - a consistent structural relationship.

Return for Risk

VMBSX vs. FEPAX — Risk / Return Rank

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

VMBSX

VMBSX Risk / Return Rank: 40
VMBSX Sharpe Ratio Rank: 38
VMBSX Sortino Ratio Rank: 41
VMBSX Omega Ratio Rank: 38
VMBSX Calmar Ratio Rank: 45
VMBSX Martin Ratio Rank: 40

FEPAX

FEPAX Risk / Return Rank: 22
FEPAX Sharpe Ratio Rank: 22
FEPAX Sortino Ratio Rank: 24
FEPAX Omega Ratio Rank: 21
FEPAX Calmar Ratio Rank: 24
FEPAX Martin Ratio Rank: 21

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.

VMBSX vs. FEPAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Mortgage-Backed Securities Index Fund Admiral Shares (VMBSX) and Fidelity Advisor Total Bond Fund Class A (FEPAX). 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.

	VMBSX	FEPAX	Difference
Sharpe ratio: Return per unit of total volatility	1.78	1.35	+0.42
Sortino ratio: Return per unit of downside risk	2.65	2.06	+0.60
Omega ratio: Gain probability vs. loss probability	1.33	1.24	+0.09
Calmar ratio: Return relative to maximum drawdown	2.54	1.78	+0.76
Martin ratio: Return relative to average drawdown	8.52	5.27	+3.25
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VMBSX vs. FEPAX - Sharpe Ratio Comparison

The current VMBSX Sharpe Ratio is 1.78, which is higher than the FEPAX Sharpe Ratio of 1.35. The chart below compares the historical Sharpe Ratios of VMBSX and FEPAX, 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

	VMBSX	FEPAX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.78	1.35	+0.42
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.07	0.03	+0.05
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.38	0.43	-0.05
Sharpe Ratio (All Time) Calculated using the full available price history	0.58	0.83	-0.25

Drawdowns

VMBSX vs. FEPAX - Drawdown Comparison

The maximum VMBSX drawdown since its inception was -17.44%, smaller than the maximum FEPAX drawdown of -18.52%. Use the drawdown chart below to compare losses from any high point for VMBSX and FEPAX.

Drawdown Indicators

	VMBSX	FEPAX	Difference
Max Drawdown Largest peak-to-trough decline	-17.44%	-18.52%	+1.08%
Max Drawdown (1Y) Largest decline over 1 year	-2.67%	-2.94%	+0.27%
Max Drawdown (3Y) Largest decline over 3 years	-7.53%	-5.89%	-1.64%
Max Drawdown (5Y) Largest decline over 5 years	-17.12%	-18.52%	+1.40%
Max Drawdown (10Y) Largest decline over 10 years	-17.44%	-18.52%	+1.08%
Current Drawdown Current decline from peak	-1.43%	-1.58%	+0.15%
Average Drawdown Average peak-to-trough decline	-2.48%	-2.62%	+0.14%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.79%	0.99%	-0.20%

Volatility

VMBSX vs. FEPAX - Volatility Comparison

Vanguard Mortgage-Backed Securities Index Fund Admiral Shares (VMBSX) has a higher volatility of 1.43% compared to Fidelity Advisor Total Bond Fund Class A (FEPAX) at 1.28%. This indicates that VMBSX's price experiences larger fluctuations and is considered to be riskier than FEPAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VMBSX	FEPAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.43%	1.28%	+0.15%
Volatility (6M) Calculated over the trailing 6-month period	2.72%	2.73%	-0.01%
Volatility (1Y) Calculated over the trailing 1-year period	3.82%	3.87%	-0.05%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.40%	5.65%	+0.75%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.86%	4.72%	+0.14%

VMBSX vs. FEPAX - Expense Ratio Comparison

VMBSX has a 0.07% expense ratio, which is lower than FEPAX's 0.75% expense ratio.

Dividends

VMBSX vs. FEPAX - Dividend Comparison

VMBSX's dividend yield for the trailing twelve months is around 4.17%, more than FEPAX's 4.06% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FEPAX Fidelity Advisor Total Bond Fund Class A	4.06%	4.07%	3.18%	3.51%	2.29%	1.68%	4.93%	2.73%	2.87%	2.49%	3.28%	3.01%
VMBSX Vanguard Mortgage-Backed Securities Index Fund Admiral Shares	4.17%	4.18%	4.24%	3.28%	2.31%	0.99%	2.00%	7.48%	2.72%	2.16%	1.98%	2.01%

Frequently Asked Questions

Can I hold both VMBSX and FEPAX in my portfolio?

With a correlation of 0.90, VMBSX and FEPAX 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, VMBSX or FEPAX?

VMBSX has higher volatility (1.43%) compared to FEPAX (1.28%). In terms of maximum drawdown, VMBSX dropped -17.44% vs FEPAX's -18.52%.

Which has better risk-adjusted returns?

VMBSX currently has the higher Sharpe Ratio (1.78 vs 1.35), 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.