VMBSX vs. FJTDX

Last updated Jun 5, 2026

VMBSX (Vanguard Mortgage-Backed Securities Index Fund Admiral Shares) and FJTDX (Fidelity Flex Conservative Income Bond Fund) are both Total Bond Market funds. Over the past 5 years, VMBSX returned 0.47%/yr vs 3.69%/yr for FJTDX. At a 0.19 correlation, their price movements are largely independent. VMBSX charges 0.07%/yr vs 0.00%/yr for FJTDX.

Performance

VMBSX vs. FJTDX - 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 Flex Conservative Income Bond Fund (FJTDX). 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 lower than FJTDX's 1.59% 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%

FJTDX

• 1D: 0.00%
• 1M: 0.35%
• YTD: 1.59%
• 6M: 1.95%
• 1Y: 4.37%
• 3Y*: 5.11%
• 5Y*: 3.69%
• 10Y*: —

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

VMBSX vs. FJTDX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018
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%	1.41%
FJTDX Fidelity Flex Conservative Income Bond Fund	1.59%	4.75%	5.69%	5.48%	1.00%	0.16%	1.57%	3.20%	0.50%

Correlation

The correlation between VMBSX and FJTDX is 0.16, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.16
Correlation (3Y) Calculated over the trailing 3-year period	0.18
Correlation (5Y) Calculated over the trailing 5-year period	0.22
Correlation (All Time) Calculated using the full available price history since Sep 4, 2018	0.19

Return for Risk

VMBSX vs. FJTDX — 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

FJTDX

FJTDX Risk / Return Rank: 99
FJTDX Sharpe Ratio Rank: 95
FJTDX Sortino Ratio Rank: 100
FJTDX Omega Ratio Rank: 100
FJTDX Calmar Ratio Rank: 100
FJTDX Martin Ratio Rank: 100

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. FJTDX - 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 Flex Conservative Income Bond Fund (FJTDX). 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	FJTDX	Difference
Sharpe ratio: Return per unit of total volatility	1.78	3.45	-1.67
Sortino ratio: Return per unit of downside risk	2.65	16.28	-13.63
Omega ratio: Gain probability vs. loss probability	1.33	6.97	-5.65
Calmar ratio: Return relative to maximum drawdown	2.54	44.20	-41.66
Martin ratio: Return relative to average drawdown	8.52	112.52	-104.00
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. FJTDX - Sharpe Ratio Comparison

The current VMBSX Sharpe Ratio is 1.78, which is lower than the FJTDX Sharpe Ratio of 3.45. The chart below compares the historical Sharpe Ratios of VMBSX and FJTDX, 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	FJTDX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.78	3.45	-1.67
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.07	2.58	-2.51
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.38	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.58	2.42	-1.84

Drawdowns

VMBSX vs. FJTDX - Drawdown Comparison

The maximum VMBSX drawdown since its inception was -17.44%, which is greater than FJTDX's maximum drawdown of -1.90%. Use the drawdown chart below to compare losses from any high point for VMBSX and FJTDX.

Drawdown Indicators

	VMBSX	FJTDX	Difference
Max Drawdown Largest peak-to-trough decline	-17.44%	-1.90%	-15.54%
Max Drawdown (1Y) Largest decline over 1 year	-2.67%	-0.10%	-2.57%
Max Drawdown (3Y) Largest decline over 3 years	-7.53%	-0.90%	-6.63%
Max Drawdown (5Y) Largest decline over 5 years	-17.12%	-0.90%	-16.22%
Max Drawdown (10Y) Largest decline over 10 years	-17.44%	—	—
Current Drawdown Current decline from peak	-1.43%	0.00%	-1.43%
Average Drawdown Average peak-to-trough decline	-2.48%	-0.08%	-2.40%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.79%	0.04%	+0.75%

Volatility

VMBSX vs. FJTDX - Volatility Comparison

Vanguard Mortgage-Backed Securities Index Fund Admiral Shares (VMBSX) has a higher volatility of 1.43% compared to Fidelity Flex Conservative Income Bond Fund (FJTDX) at 0.35%. This indicates that VMBSX's price experiences larger fluctuations and is considered to be riskier than FJTDX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VMBSX	FJTDX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.43%	0.35%	+1.08%
Volatility (6M) Calculated over the trailing 6-month period	2.72%	0.86%	+1.86%
Volatility (1Y) Calculated over the trailing 1-year period	3.82%	1.28%	+2.54%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	6.40%	1.44%	+4.96%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.86%	1.28%	+3.58%

VMBSX vs. FJTDX - Expense Ratio Comparison

VMBSX has a 0.07% expense ratio, which is higher than FJTDX's 0.00% expense ratio. However, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

VMBSX vs. FJTDX - Dividend Comparison

VMBSX's dividend yield for the trailing twelve months is around 4.17%, less than FJTDX's 4.37% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FJTDX Fidelity Flex Conservative Income Bond Fund	4.37%	4.63%	5.42%	4.70%	1.39%	0.36%	1.45%	2.65%	1.17%	0.00%	0.00%	0.00%
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 FJTDX in my portfolio?

VMBSX and FJTDX have a correlation of 0.16, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, VMBSX or FJTDX?

VMBSX has higher volatility (1.43%) compared to FJTDX (0.35%). In terms of maximum drawdown, VMBSX dropped -17.44% vs FJTDX's -1.90%.

Which has better risk-adjusted returns?

FJTDX currently has the higher Sharpe Ratio (3.45 vs 1.78), 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.