BUFTX vs. NEEIX

Last updated Jun 5, 2026

BUFTX (Buffalo Discovery Fund) and NEEIX (Needham Growth Fund Institutional Class) are both Mid Cap Growth Equities funds. Over the past 5 years, BUFTX returned -1.10%/yr vs 15.90%/yr for NEEIX. Their correlation of 0.84 suggests significant overlap in exposure. BUFTX charges 1.00%/yr vs 1.21%/yr for NEEIX.

Performance

BUFTX vs. NEEIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Buffalo Discovery Fund (BUFTX) and Needham Growth Fund Institutional Class (NEEIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, BUFTX achieves a -3.41% return, which is significantly lower than NEEIX's 59.32% return.

BUFTX

• 1D: -1.25%
• 1M: 1.34%
• YTD: -3.41%
• 6M: -4.97%
• 1Y: -7.07%
• 3Y*: 3.88%
• 5Y*: -1.10%
• 10Y*: 7.57%

NEEIX

• 1D: -0.18%
• 1M: 14.36%
• YTD: 59.32%
• 6M: 55.88%
• 1Y: 95.96%
• 3Y*: 30.80%
• 5Y*: 15.90%
• 10Y*: —

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

BUFTX vs. NEEIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
BUFTX Buffalo Discovery Fund	-3.41%	-1.83%	5.31%	24.30%	-28.78%	11.55%	33.90%	31.62%	-6.52%	24.63%
NEEIX Needham Growth Fund Institutional Class	59.32%	9.32%	19.26%	27.30%	-33.26%	28.13%	42.39%	43.15%	-10.13%	8.47%

Correlation

The correlation between BUFTX and NEEIX is 0.69, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.69
Correlation (3Y) Calculated over the trailing 3-year period	0.76
Correlation (5Y) Calculated over the trailing 5-year period	0.83
Correlation (All Time) Calculated using the full available price history since Jan 4, 2017	0.84

The correlation between BUFTX and NEEIX shifts across timeframes, from 0.69 (1 year) to 0.84 (all time), reflecting how their relationship changes across market environments.

Return for Risk

BUFTX vs. NEEIX — 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: 1
BUFTX Calmar Ratio Rank: 1
BUFTX Martin Ratio Rank: 1

NEEIX

NEEIX Risk / Return Rank: 92
NEEIX Sharpe Ratio Rank: 97
NEEIX Sortino Ratio Rank: 87
NEEIX Omega Ratio Rank: 83
NEEIX Calmar Ratio Rank: 97
NEEIX Martin Ratio Rank: 97

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. NEEIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Buffalo Discovery Fund (BUFTX) and Needham Growth Fund Institutional Class (NEEIX). 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.

	BUFTX	NEEIX	Difference
Sharpe ratio: Return per unit of total volatility	-0.42	3.65	-4.06
Sortino ratio: Return per unit of downside risk	-0.49	4.20	-4.69
Omega ratio: Gain probability vs. loss probability	0.94	1.55	-0.60
Calmar ratio: Return relative to maximum drawdown	-0.34	7.45	-7.78
Martin ratio: Return relative to average drawdown	-0.79	25.35	-26.14
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

BUFTX vs. NEEIX - Sharpe Ratio Comparison

The current BUFTX Sharpe Ratio is -0.42, which is lower than the NEEIX Sharpe Ratio of 3.65. The chart below compares the historical Sharpe Ratios of BUFTX and NEEIX, 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

	BUFTX	NEEIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	-0.42	3.65	-4.06
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	-0.05	0.56	-0.62
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.37	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.36	0.67	-0.31

Drawdowns

BUFTX vs. NEEIX - Drawdown Comparison

The maximum BUFTX drawdown since its inception was -60.45%, which is greater than NEEIX's maximum drawdown of -43.11%. Use the drawdown chart below to compare losses from any high point for BUFTX and NEEIX.

Drawdown Indicators

	BUFTX	NEEIX	Difference
Max Drawdown Largest peak-to-trough decline	-60.45%	-43.11%	-17.34%
Max Drawdown (1Y) Largest decline over 1 year	-19.03%	-13.22%	-5.81%
Max Drawdown (3Y) Largest decline over 3 years	-22.10%	-36.13%	+14.03%
Max Drawdown (5Y) Largest decline over 5 years	-36.36%	-43.11%	+6.75%
Max Drawdown (10Y) Largest decline over 10 years	-36.36%	—	—
Current Drawdown Current decline from peak	-14.34%	-0.18%	-14.16%
Average Drawdown Average peak-to-trough decline	-11.32%	-10.86%	-0.46%
Ulcer Index Depth and duration of drawdowns from previous peaks	8.09%	3.88%	+4.21%

Volatility

BUFTX vs. NEEIX - Volatility Comparison

The current volatility for Buffalo Discovery Fund (BUFTX) is 3.88%, while Needham Growth Fund Institutional Class (NEEIX) has a volatility of 9.68%. This indicates that BUFTX experiences smaller price fluctuations and is considered to be less risky than NEEIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	BUFTX	NEEIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.88%	9.68%	-5.80%
Volatility (6M) Calculated over the trailing 6-month period	11.91%	20.86%	-8.95%
Volatility (1Y) Calculated over the trailing 1-year period	15.32%	27.10%	-11.78%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	21.07%	28.31%	-7.24%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	20.39%	25.79%	-5.40%

BUFTX vs. NEEIX - Expense Ratio Comparison

BUFTX has a 1.00% expense ratio, which is lower than NEEIX's 1.21% expense ratio.

Dividends

BUFTX vs. NEEIX - Dividend Comparison

BUFTX's dividend yield for the trailing twelve months is around 21.89%, more than NEEIX's 4.49% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
BUFTX Buffalo Discovery Fund	21.89%	21.15%	10.00%	0.00%	7.08%	15.11%	7.98%	14.81%	7.01%	4.64%	0.00%	7.56%
NEEIX Needham Growth Fund Institutional Class	4.49%	7.16%	7.48%	0.00%	1.72%	6.70%	5.58%	11.09%	17.58%	9.64%	0.00%	0.00%

Frequently Asked Questions

Can I hold both BUFTX and NEEIX in my portfolio?

BUFTX and NEEIX have a correlation of 0.69, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, BUFTX or NEEIX?

NEEIX has higher volatility (9.68%) compared to BUFTX (3.88%). In terms of maximum drawdown, BUFTX dropped -60.45% vs NEEIX's -43.11%.

Which has better risk-adjusted returns?

NEEIX currently has the higher Sharpe Ratio (3.65 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.