FMDGX vs. SSFDX

Last updated Jun 4, 2026

FMDGX (Fidelity Mid Cap Growth Index Fund) and SSFDX (State Street Aggregate Bond Index Fund) are both mutual funds - FMDGX is a Mid Cap Growth Equities fund managed by Fidelity, while SSFDX is a Intermediate Core Bond fund managed by State Street. Over the past 5 years, FMDGX returned 7.23%/yr vs 0.01%/yr for SSFDX. At a 0.11 correlation, their price movements are largely independent. FMDGX charges 0.05%/yr vs 0.23%/yr for SSFDX.

Performance

FMDGX vs. SSFDX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Mid Cap Growth Index Fund (FMDGX) and State Street Aggregate Bond Index Fund (SSFDX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, FMDGX achieves a 4.88% return, which is significantly higher than SSFDX's 0.42% return.

FMDGX

• 1D: -0.22%
• 1M: 5.21%
• YTD: 4.88%
• 6M: 3.96%
• 1Y: 6.81%
• 3Y*: 16.42%
• 5Y*: 7.23%
• 10Y*: —

SSFDX

• 1D: 0.05%
• 1M: 0.49%
• YTD: 0.42%
• 6M: 0.33%
• 1Y: 5.38%
• 3Y*: 3.86%
• 5Y*: 0.01%
• 10Y*: -19.40%

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

FMDGX vs. SSFDX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019
FMDGX Fidelity Mid Cap Growth Index Fund	4.88%	8.60%	22.03%	25.79%	-26.67%	12.67%	34.84%	4.63%
SSFDX State Street Aggregate Bond Index Fund	0.42%	6.80%	1.36%	5.39%	-13.36%	-1.98%	-89.24%	2.31%

Correlation

The correlation between FMDGX and SSFDX is 0.27, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.27
Correlation (3Y) Calculated over the trailing 3-year period	0.22
Correlation (5Y) Calculated over the trailing 5-year period	0.17
Correlation (All Time) Calculated using the full available price history since Jul 18, 2019	0.11

The correlation between FMDGX and SSFDX shifts across timeframes, from 0.11 (all time) to 0.27 (1 year), reflecting how their relationship changes across market environments.

Return for Risk

FMDGX vs. SSFDX — Risk / Return Rank

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

FMDGX

FMDGX Risk / Return Rank: 6
FMDGX Sharpe Ratio Rank: 6
FMDGX Sortino Ratio Rank: 6
FMDGX Omega Ratio Rank: 6
FMDGX Calmar Ratio Rank: 6
FMDGX Martin Ratio Rank: 6

SSFDX

SSFDX Risk / Return Rank: 26
SSFDX Sharpe Ratio Rank: 26
SSFDX Sortino Ratio Rank: 27
SSFDX Omega Ratio Rank: 24
SSFDX Calmar Ratio Rank: 27
SSFDX Martin Ratio Rank: 24

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.

FMDGX vs. SSFDX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Mid Cap Growth Index Fund (FMDGX) and State Street Aggregate Bond Index Fund (SSFDX). 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.

	FMDGX	SSFDX	Difference
Sharpe ratio: Return per unit of total volatility	0.49	1.44	-0.96
Sortino ratio: Return per unit of downside risk	0.80	2.16	-1.37
Omega ratio: Gain probability vs. loss probability	1.09	1.26	-0.16
Calmar ratio: Return relative to maximum drawdown	0.54	1.95	-1.41
Martin ratio: Return relative to average drawdown	1.58	5.97	-4.39
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FMDGX vs. SSFDX - Sharpe Ratio Comparison

The current FMDGX Sharpe Ratio is 0.49, which is lower than the SSFDX Sharpe Ratio of 1.44. The chart below compares the historical Sharpe Ratios of FMDGX and SSFDX, 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

	FMDGX	SSFDX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	0.49	1.44	-0.96
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.32	0.00	+0.32
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	-0.61	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.45	-0.56	+1.01

Drawdowns

FMDGX vs. SSFDX - Drawdown Comparison

The maximum FMDGX drawdown since its inception was -38.59%, smaller than the maximum SSFDX drawdown of -92.69%. Use the drawdown chart below to compare losses from any high point for FMDGX and SSFDX.

Drawdown Indicators

	FMDGX	SSFDX	Difference
Max Drawdown Largest peak-to-trough decline	-38.59%	-92.69%	+54.10%
Max Drawdown (1Y) Largest decline over 1 year	-14.75%	-2.75%	-12.00%
Max Drawdown (3Y) Largest decline over 3 years	-25.30%	-6.13%	-19.17%
Max Drawdown (5Y) Largest decline over 5 years	-38.59%	-18.19%	-20.40%
Max Drawdown (10Y) Largest decline over 10 years	—	-92.69%	—
Current Drawdown Current decline from peak	-1.09%	-90.13%	+89.04%
Average Drawdown Average peak-to-trough decline	-11.21%	-48.03%	+36.82%
Ulcer Index Depth and duration of drawdowns from previous peaks	5.05%	0.90%	+4.15%

Volatility

FMDGX vs. SSFDX - Volatility Comparison

Fidelity Mid Cap Growth Index Fund (FMDGX) has a higher volatility of 3.52% compared to State Street Aggregate Bond Index Fund (SSFDX) at 1.29%. This indicates that FMDGX's price experiences larger fluctuations and is considered to be riskier than SSFDX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FMDGX	SSFDX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.52%	1.29%	+2.23%
Volatility (6M) Calculated over the trailing 6-month period	12.64%	2.66%	+9.98%
Volatility (1Y) Calculated over the trailing 1-year period	16.46%	3.74%	+12.72%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	22.37%	5.93%	+16.44%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	24.32%	31.82%	-7.50%

FMDGX vs. SSFDX - Expense Ratio Comparison

FMDGX has a 0.05% expense ratio, which is lower than SSFDX's 0.23% expense ratio. Despite the difference, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

FMDGX vs. SSFDX - Dividend Comparison

FMDGX's dividend yield for the trailing twelve months is around 1.77%, less than SSFDX's 4.11% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FMDGX Fidelity Mid Cap Growth Index Fund	1.77%	1.85%	0.47%	0.63%	0.81%	6.43%	0.36%	0.29%	0.00%	0.00%	0.00%	0.00%
SSFDX State Street Aggregate Bond Index Fund	4.11%	3.64%	3.59%	2.95%	2.27%	3.12%	8.84%	3.15%	2.79%	2.43%	2.19%	4.63%

Frequently Asked Questions

Can I hold both FMDGX and SSFDX in my portfolio?

FMDGX and SSFDX have a correlation of 0.27, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, FMDGX or SSFDX?

FMDGX has higher volatility (3.52%) compared to SSFDX (1.29%). In terms of maximum drawdown, FMDGX dropped -38.59% vs SSFDX's -92.69%.

Which has better risk-adjusted returns?

SSFDX currently has the higher Sharpe Ratio (1.44 vs 0.49), 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.