GWGIX vs. VMFGX

Last updated Jun 26, 2026

GWGIX (AMG GW&K Small/Mid Cap Fund) and VMFGX (Vanguard S&P Mid-Cap 400 Growth Index Fund Institutional Shares) are both Mid Cap Growth Equities funds. Over the past 10 years, GWGIX returned 11.71%/yr vs 12.03%/yr for VMFGX. With a 0.95 correlation, they move nearly in lockstep. GWGIX charges 0.87%/yr vs 0.08%/yr for VMFGX.

Performance

GWGIX vs. VMFGX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in AMG GW&K Small/Mid Cap Fund (GWGIX) and Vanguard S&P Mid-Cap 400 Growth Index Fund Institutional Shares (VMFGX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

The year-to-date returns for both investments are quite close, with GWGIX having a 18.23% return and VMFGX slightly higher at 18.90%. Both investments have delivered pretty close results over the past 10 years, with GWGIX having a 11.71% annualized return and VMFGX not far ahead at 12.03%.

GWGIX

• 1D: 1.25%
• 1M: 2.75%
• YTD: 18.23%
• 6M: 15.65%
• 1Y: 26.37%
• 3Y*: 14.30%
• 5Y*: 6.21%
• 10Y*: 11.71%

VMFGX

• 1D: 0.30%
• 1M: 0.90%
• YTD: 18.90%
• 6M: 16.25%
• 1Y: 29.62%
• 3Y*: 17.91%
• 5Y*: 8.20%
• 10Y*: 12.03%

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

GWGIX vs. VMFGX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
GWGIX AMG GW&K Small/Mid Cap Fund	18.23%	1.53%	10.85%	14.76%	-18.09%	26.01%	23.31%	31.02%	-8.14%	15.44%
VMFGX Vanguard S&P Mid-Cap 400 Growth Index Fund Institutional Shares	18.90%	7.43%	15.86%	17.42%	-18.99%	18.83%	22.61%	26.20%	-10.39%	19.87%

Correlation

The correlation between GWGIX and VMFGX is 0.92, 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	0.92
Correlation (3Y) Calculated over the trailing 3-year period	0.94
Correlation (5Y) Calculated over the trailing 5-year period	0.95
Correlation (10Y) Calculated over the trailing 10-year period	0.95
Correlation (All Time) Calculated using the full available price history since Jan 4, 2016	0.95

The correlation between GWGIX and VMFGX has been stable across timeframes, ranging from 0.92 to 0.95 - a consistent structural relationship.

Return for Risk

GWGIX vs. VMFGX — Risk / Return Rank

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

GWGIX

GWGIX Risk / Return Rank: 43
GWGIX Sharpe Ratio Rank: 35
GWGIX Sortino Ratio Rank: 35
GWGIX Omega Ratio Rank: 33
GWGIX Calmar Ratio Rank: 61
GWGIX Martin Ratio Rank: 50

VMFGX

VMFGX Risk / Return Rank: 56
VMFGX Sharpe Ratio Rank: 46
VMFGX Sortino Ratio Rank: 46
VMFGX Omega Ratio Rank: 41
VMFGX Calmar Ratio Rank: 74
VMFGX Martin Ratio Rank: 72

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.

GWGIX vs. VMFGX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for AMG GW&K Small/Mid Cap Fund (GWGIX) and Vanguard S&P Mid-Cap 400 Growth Index Fund Institutional Shares (VMFGX). 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.

Values are calculated on a 1-year rolling basis and updated daily. Risk-adjusted metrics are more stable over longer periods — use the period switch above to explore them.

	GWGIX	VMFGX	Difference
Sharpe ratio: Return per unit of total volatility	1.42	1.65	-0.23
Sortino ratio: Return per unit of downside risk	2.06	2.37	-0.31
Omega ratio: Gain probability vs. loss probability	1.25	1.29	-0.04
Calmar ratio: Return relative to maximum drawdown	2.56	2.91	-0.35
Martin ratio: Return relative to average drawdown	8.77	11.48	-2.71

GWGIX vs. VMFGX - Sharpe Ratio Comparison

The current GWGIX Sharpe Ratio is 1.42, which is comparable to the VMFGX Sharpe Ratio of 1.65. The chart below compares the historical Sharpe Ratios of GWGIX and VMFGX, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Drawdowns

GWGIX vs. VMFGX - Drawdown Comparison

The maximum GWGIX drawdown since its inception was -37.41%, roughly equal to the maximum VMFGX drawdown of -39.15%. Use the drawdown chart below to compare losses from any high point for GWGIX and VMFGX.

Drawdown Indicators

	GWGIX	VMFGX	Difference
Max Drawdown Largest peak-to-trough decline	-37.41%	-39.15%	+1.74%
Max Drawdown (1Y) Largest decline over 1 year	-9.90%	-9.91%	+0.01%
Max Drawdown (3Y) Largest decline over 3 years	-25.85%	-25.45%	-0.40%
Max Drawdown (5Y) Largest decline over 5 years	-27.18%	-29.25%	+2.07%
Max Drawdown (10Y) Largest decline over 10 years	-37.41%	-39.15%	+1.74%
Current Drawdown Current decline from peak	-0.35%	-1.32%	+0.97%
Average Drawdown Average peak-to-trough decline	-6.93%	-5.69%	-1.24%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.87%	2.50%	+0.37%

Volatility

GWGIX vs. VMFGX - Volatility Comparison

AMG GW&K Small/Mid Cap Fund (GWGIX) and Vanguard S&P Mid-Cap 400 Growth Index Fund Institutional Shares (VMFGX) have volatilities of 5.76% and 5.82%, respectively, indicating that both stocks experience similar levels of price fluctuations. This suggests that the risk associated with both stocks, as measured by volatility, is nearly the same. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	GWGIX	VMFGX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.76%	5.82%	-0.06%
Volatility (6M) Calculated over the trailing 6-month period	13.26%	13.74%	-0.48%
Volatility (1Y) Calculated over the trailing 1-year period	17.86%	17.46%	+0.40%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	19.99%	20.70%	-0.71%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	20.24%	21.07%	-0.83%

GWGIX vs. VMFGX - Expense Ratio Comparison

GWGIX has a 0.87% expense ratio, which is higher than VMFGX's 0.08% expense ratio.

Dividends

GWGIX vs. VMFGX - Dividend Comparison

GWGIX has not paid dividends to shareholders, while VMFGX's dividend yield for the trailing twelve months is around 0.59%.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
GWGIX AMG GW&K Small/Mid Cap Fund	0.00%	0.00%	0.95%	0.19%	4.22%	5.45%	0.12%	0.37%	2.48%	1.46%	0.05%	0.00%
VMFGX Vanguard S&P Mid-Cap 400 Growth Index Fund Institutional Shares	0.59%	0.70%	0.84%	1.21%	1.12%	0.53%	0.79%	1.22%	1.18%	0.93%	1.14%	1.14%

Frequently Asked Questions

Can I hold both GWGIX and VMFGX in my portfolio?

With a correlation of 0.92, GWGIX and VMFGX 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, GWGIX or VMFGX?

VMFGX has higher volatility (5.82%) compared to GWGIX (5.76%). In terms of maximum drawdown, GWGIX dropped -37.41% vs VMFGX's -39.15%.

Which has better risk-adjusted returns?

VMFGX currently has the higher Sharpe Ratio (1.65 vs 1.42), 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.