FMDGX vs. BBMIX

Last updated Jun 4, 2026

FMDGX (Fidelity Mid Cap Growth Index Fund) and BBMIX (BBH Select Series - Mid Cap Fund) are both Mid Cap Growth Equities funds. Over the past 5 years, FMDGX returned 7.23%/yr vs 3.05%/yr for BBMIX. Their correlation of 0.84 suggests significant overlap in exposure. FMDGX charges 0.05%/yr vs 0.90%/yr for BBMIX.

Performance

FMDGX vs. BBMIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity Mid Cap Growth Index Fund (FMDGX) and BBH Select Series - Mid Cap Fund (BBMIX). 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 BBMIX's 2.86% return.

FMDGX

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

BBMIX

• 1D: 0.00%
• 1M: 0.00%
• YTD: 2.86%
• 6M: 2.86%
• 1Y: 1.23%
• 3Y*: 6.69%
• 5Y*: 3.05%
• 10Y*: —

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

FMDGX vs. BBMIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021
FMDGX Fidelity Mid Cap Growth Index Fund	4.88%	8.60%	22.03%	25.79%	-26.67%	10.09%
BBMIX BBH Select Series - Mid Cap Fund	2.86%	-6.45%	11.41%	26.01%	-24.76%	13.50%

Correlation

The correlation between FMDGX and BBMIX is 0.44, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.44
Correlation (3Y) Calculated over the trailing 3-year period	0.75
Correlation (5Y) Calculated over the trailing 5-year period	0.84
Correlation (All Time) Calculated using the full available price history since May 25, 2021	0.84

Over the past year, the correlation between FMDGX and BBMIX has dropped to 0.44 - well below their long-term average of 0.84, suggesting their price drivers have been diverging.

Return for Risk

FMDGX vs. BBMIX — 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

BBMIX

BBMIX Risk / Return Rank: 4
BBMIX Sharpe Ratio Rank: 4
BBMIX Sortino Ratio Rank: 4
BBMIX Omega Ratio Rank: 4
BBMIX Calmar Ratio Rank: 4
BBMIX Martin Ratio Rank: 4

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. BBMIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity Mid Cap Growth Index Fund (FMDGX) and BBH Select Series - Mid Cap Fund (BBMIX). 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	BBMIX	Difference
Sharpe ratio: Return per unit of total volatility	0.49	0.24	+0.24
Sortino ratio: Return per unit of downside risk	0.80	0.43	+0.37
Omega ratio: Gain probability vs. loss probability	1.09	1.07	+0.03
Calmar ratio: Return relative to maximum drawdown	0.54	0.32	+0.23
Martin ratio: Return relative to average drawdown	1.58	0.50	+1.08
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. BBMIX - Sharpe Ratio Comparison

The current FMDGX Sharpe Ratio is 0.49, which is higher than the BBMIX Sharpe Ratio of 0.24. The chart below compares the historical Sharpe Ratios of FMDGX and BBMIX, 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	BBMIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	0.49	0.24	+0.24
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.32	0.16	+0.16
Sharpe Ratio (All Time) Calculated using the full available price history	0.45	0.15	+0.30

Drawdowns

FMDGX vs. BBMIX - Drawdown Comparison

The maximum FMDGX drawdown since its inception was -38.59%, which is greater than BBMIX's maximum drawdown of -28.90%. Use the drawdown chart below to compare losses from any high point for FMDGX and BBMIX.

Drawdown Indicators

	FMDGX	BBMIX	Difference
Max Drawdown Largest peak-to-trough decline	-38.59%	-28.90%	-9.69%
Max Drawdown (1Y) Largest decline over 1 year	-14.75%	-8.89%	-5.86%
Max Drawdown (3Y) Largest decline over 3 years	-25.30%	-23.79%	-1.51%
Max Drawdown (5Y) Largest decline over 5 years	-38.59%	-28.90%	-9.69%
Current Drawdown Current decline from peak	-1.09%	-11.28%	+10.19%
Average Drawdown Average peak-to-trough decline	-11.21%	-10.51%	-0.70%
Ulcer Index Depth and duration of drawdowns from previous peaks	5.05%	5.68%	-0.63%

Volatility

FMDGX vs. BBMIX - Volatility Comparison

Fidelity Mid Cap Growth Index Fund (FMDGX) has a higher volatility of 3.52% compared to BBH Select Series - Mid Cap Fund (BBMIX) at 0.00%. This indicates that FMDGX's price experiences larger fluctuations and is considered to be riskier than BBMIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FMDGX	BBMIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.52%	0.00%	+3.52%
Volatility (6M) Calculated over the trailing 6-month period	12.64%	6.37%	+6.27%
Volatility (1Y) Calculated over the trailing 1-year period	16.46%	11.62%	+4.84%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	22.37%	19.72%	+2.65%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	24.32%	19.68%	+4.64%

FMDGX vs. BBMIX - Expense Ratio Comparison

FMDGX has a 0.05% expense ratio, which is lower than BBMIX's 0.90% expense ratio.

Dividends

FMDGX vs. BBMIX - Dividend Comparison

FMDGX's dividend yield for the trailing twelve months is around 1.77%, while BBMIX has not paid dividends to shareholders.

Position	TTM	2025	2024	2023	2022	2021	2020	2019
BBMIX BBH Select Series - Mid Cap Fund	0.00%	0.00%	0.32%	0.10%	0.00%	0.00%	0.00%	0.00%
FMDGX Fidelity Mid Cap Growth Index Fund	1.77%	1.85%	0.47%	0.63%	0.81%	6.43%	0.36%	0.29%

Frequently Asked Questions

Can I hold both FMDGX and BBMIX in my portfolio?

FMDGX and BBMIX have a correlation of 0.44, 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 BBMIX?

FMDGX has higher volatility (3.52%) compared to BBMIX (0.00%). In terms of maximum drawdown, FMDGX dropped -38.59% vs BBMIX's -28.90%.

Which has better risk-adjusted returns?

FMDGX currently has the higher Sharpe Ratio (0.49 vs 0.24), 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.