BUFTX vs. VMGMX

Last updated Jul 16, 2026

BUFTX (Buffalo Discovery Fund) and VMGMX (Vanguard Mid-Cap Growth Index Fund Admiral Shares) are both Mid Cap Growth Equities funds. Over the past 10 years, BUFTX returned 7.46%/yr vs 11.84%/yr for VMGMX. With a 0.95 correlation, they move nearly in lockstep. BUFTX charges 1.00%/yr vs 0.07%/yr for VMGMX.

Performance

BUFTX vs. VMGMX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Buffalo Discovery Fund (BUFTX) and Vanguard Mid-Cap Growth Index Fund Admiral Shares (VMGMX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, BUFTX achieves a -2.61% return, which is significantly lower than VMGMX's 8.12% return. Over the past 10 years, BUFTX has underperformed VMGMX with an annualized return of 7.46%, while VMGMX has yielded a comparatively higher 11.84% annualized return.

BUFTX

• 1D: 0.99%
• 1M: 0.38%
• 6M: -5.58%
• YTD: -2.61%
• 1Y: -5.82%
• 3Y*: 2.11%
• 5Y*: -1.42%
• 10Y*: 7.46%

VMGMX

• 1D: 0.43%
• 1M: -1.37%
• 6M: 5.74%
• YTD: 8.12%
• 1Y: 6.97%
• 3Y*: 13.39%
• 5Y*: 5.94%
• 10Y*: 11.84%

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

BUFTX vs. VMGMX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
BUFTX Buffalo Discovery Fund	-2.61%	-1.83%	5.31%	24.30%	-28.78%	11.55%	33.90%	31.62%	-6.52%	25.43%
VMGMX Vanguard Mid-Cap Growth Index Fund Admiral Shares	8.12%	10.69%	15.65%	23.93%	-28.84%	20.48%	34.45%	33.85%	-5.61%	21.83%

Correlation

The correlation between BUFTX and VMGMX 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	0.93
Correlation (5Y) Calculated over the trailing 5-year period	0.96
Correlation (10Y) Calculated over the trailing 10-year period	0.96
Correlation (All Time) Calculated using the full available price history since Sep 27, 2011	0.95

The correlation between BUFTX and VMGMX has been stable across timeframes, ranging from 0.92 to 0.96 - a consistent structural relationship.

Return for Risk

BUFTX vs. VMGMX — Risk / Return Rank

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

BUFTX

BUFTX Risk / Return Rank: 1
BUFTX Sharpe Ratio Rank: 1
BUFTX Sortino Ratio Rank: 1
BUFTX Omega Ratio Rank: 2
BUFTX Calmar Ratio Rank: 1
BUFTX Martin Ratio Rank: 1

VMGMX

VMGMX Risk / Return Rank: 7
VMGMX Sharpe Ratio Rank: 7
VMGMX Sortino Ratio Rank: 7
VMGMX Omega Ratio Rank: 6
VMGMX Calmar Ratio Rank: 6
VMGMX Martin Ratio Rank: 7

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.

BUFTX vs. VMGMX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Buffalo Discovery Fund (BUFTX) and Vanguard Mid-Cap Growth Index Fund Admiral Shares (VMGMX). 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.

	BUFTX	VMGMX	Difference
Sharpe ratio: Return per unit of total volatility	-0.42	0.34	-0.77
Sortino ratio: Return per unit of downside risk	-0.49	0.60	-1.09
Omega ratio: Gain probability vs. loss probability	0.94	1.07	-0.12
Calmar ratio: Return relative to maximum drawdown	-0.36	0.37	-0.73
Martin ratio: Return relative to average drawdown	-0.79	1.10	-1.89

BUFTX vs. VMGMX - Sharpe Ratio Comparison

The current BUFTX Sharpe Ratio is -0.42, which is lower than the VMGMX Sharpe Ratio of 0.34. The chart below compares the historical Sharpe Ratios of BUFTX and VMGMX, 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

BUFTX vs. VMGMX - Drawdown Comparison

The maximum BUFTX drawdown since its inception was -60.45%, which is greater than VMGMX's maximum drawdown of -37.17%. Use the drawdown chart below to compare losses from any high point for BUFTX and VMGMX.

Drawdown Indicators

	BUFTX	VMGMX	Difference
Max Drawdown Largest peak-to-trough decline	-60.45%	-37.17%	-23.28%
Max Drawdown (1Y) Largest decline over 1 year	-19.03%	-15.95%	-3.08%
Max Drawdown (3Y) Largest decline over 3 years	-22.10%	-21.65%	-0.45%
Max Drawdown (5Y) Largest decline over 5 years	-36.36%	-37.17%	+0.81%
Max Drawdown (10Y) Largest decline over 10 years	-36.36%	-37.17%	+0.81%
Current Drawdown Current decline from peak	-13.63%	-1.85%	-11.78%
Average Drawdown Average peak-to-trough decline	-11.33%	-6.98%	-4.35%
Ulcer Index Depth and duration of drawdowns from previous peaks	8.72%	5.35%	+3.37%

Volatility

BUFTX vs. VMGMX - Volatility Comparison

The current volatility for Buffalo Discovery Fund (BUFTX) is 4.82%, while Vanguard Mid-Cap Growth Index Fund Admiral Shares (VMGMX) has a volatility of 5.47%. This indicates that BUFTX experiences smaller price fluctuations and is considered to be less risky than VMGMX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	BUFTX	VMGMX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.82%	5.47%	-0.65%
Volatility (6M) Calculated over the trailing 6-month period	13.12%	13.89%	-0.77%
Volatility (1Y) Calculated over the trailing 1-year period	16.35%	17.16%	-0.81%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	21.24%	21.62%	-0.38%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	20.41%	21.02%	-0.61%

BUFTX vs. VMGMX - Expense Ratio Comparison

BUFTX has a 1.00% expense ratio, which is higher than VMGMX's 0.07% expense ratio.

Dividends

BUFTX vs. VMGMX - Dividend Comparison

BUFTX's dividend yield for the trailing twelve months is around 21.71%, more than VMGMX's 0.60% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
BUFTX Buffalo Discovery Fund	21.71%	21.15%	10.00%	0.00%	7.08%	15.11%	7.98%	14.81%	7.01%	4.64%	0.00%	7.56%
VMGMX Vanguard Mid-Cap Growth Index Fund Admiral Shares	0.60%	0.64%	0.67%	0.71%	0.78%	0.34%	0.56%	0.78%	0.84%	0.72%	0.81%	0.82%

Frequently Asked Questions

Can I hold both BUFTX and VMGMX in my portfolio?

With a correlation of 0.92, BUFTX and VMGMX 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, BUFTX or VMGMX?

VMGMX has higher volatility (5.47%) compared to BUFTX (4.82%). In terms of maximum drawdown, BUFTX dropped -60.45% vs VMGMX's -37.17%.

Which has better risk-adjusted returns?

VMGMX currently has the higher Sharpe Ratio (0.34 vs -0.42), 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.