COBYX vs. BESIX

Last updated Jun 5, 2026

COBYX (The Cook & Bynum Fund) and BESIX (William Blair Emerging Markets Small Cap Growth Fund) are both Emerging Markets Diversified funds. Over the past 10 years, COBYX returned 4.70%/yr vs 9.82%/yr for BESIX. At a 0.37 correlation, their price movements are largely independent. COBYX charges 1.49%/yr vs 1.30%/yr for BESIX.

Performance

COBYX vs. BESIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in The Cook & Bynum Fund (COBYX) and William Blair Emerging Markets Small Cap Growth Fund (BESIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, COBYX achieves a 9.83% return, which is significantly lower than BESIX's 22.17% return. Over the past 10 years, COBYX has underperformed BESIX with an annualized return of 4.70%, while BESIX has yielded a comparatively higher 9.82% annualized return.

COBYX

• 1D: -0.82%
• 1M: 0.68%
• YTD: 9.83%
• 6M: 12.54%
• 1Y: 14.12%
• 3Y*: 8.68%
• 5Y*: 7.72%
• 10Y*: 4.70%

BESIX

• 1D: 0.40%
• 1M: -0.36%
• YTD: 22.17%
• 6M: 24.20%
• 1Y: 41.81%
• 3Y*: 19.47%
• 5Y*: 6.85%
• 10Y*: 9.82%

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

COBYX vs. BESIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
COBYX The Cook & Bynum Fund	9.83%	20.50%	-10.32%	16.73%	9.28%	9.05%	-10.97%	9.40%	-13.40%	15.12%
BESIX William Blair Emerging Markets Small Cap Growth Fund	22.17%	13.93%	8.37%	22.25%	-27.95%	15.52%	32.60%	20.58%	-23.29%	40.54%

Correlation

The correlation between COBYX and BESIX is 0.14, which is low. Their price movements are largely independent, making them effective diversification partners.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.14
Correlation (3Y) Calculated over the trailing 3-year period	0.29
Correlation (5Y) Calculated over the trailing 5-year period	0.34
Correlation (10Y) Calculated over the trailing 10-year period	0.36
Correlation (All Time) Calculated using the full available price history since Jan 3, 2013	0.37

Over the past year, the correlation between COBYX and BESIX has dropped to 0.14 - well below their long-term average of 0.37, suggesting their price drivers have been diverging.

Return for Risk

COBYX vs. BESIX — Risk / Return Rank

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

COBYX

COBYX Risk / Return Rank: 19
COBYX Sharpe Ratio Rank: 18
COBYX Sortino Ratio Rank: 19
COBYX Omega Ratio Rank: 18
COBYX Calmar Ratio Rank: 20
COBYX Martin Ratio Rank: 20

BESIX

BESIX Risk / Return Rank: 69
BESIX Sharpe Ratio Rank: 72
BESIX Sortino Ratio Rank: 62
BESIX Omega Ratio Rank: 64
BESIX Calmar Ratio Rank: 83
BESIX Martin Ratio Rank: 66

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.

COBYX vs. BESIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for The Cook & Bynum Fund (COBYX) and William Blair Emerging Markets Small Cap Growth Fund (BESIX). 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.

	COBYX	BESIX	Difference
Sharpe ratio: Return per unit of total volatility	1.21	2.45	-1.24
Sortino ratio: Return per unit of downside risk	1.82	3.27	-1.45
Omega ratio: Gain probability vs. loss probability	1.22	1.44	-0.22
Calmar ratio: Return relative to maximum drawdown	1.59	3.82	-2.22
Martin ratio: Return relative to average drawdown	5.05	12.64	-7.60
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

COBYX vs. BESIX - Sharpe Ratio Comparison

The current COBYX Sharpe Ratio is 1.21, which is lower than the BESIX Sharpe Ratio of 2.45. The chart below compares the historical Sharpe Ratios of COBYX and BESIX, 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

	COBYX	BESIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.21	2.45	-1.24
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.56	0.46	+0.10
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.35	0.61	-0.26
Sharpe Ratio (All Time) Calculated using the full available price history	0.38	0.67	-0.29

Drawdowns

COBYX vs. BESIX - Drawdown Comparison

The maximum COBYX drawdown since its inception was -34.18%, smaller than the maximum BESIX drawdown of -38.05%. Use the drawdown chart below to compare losses from any high point for COBYX and BESIX.

Drawdown Indicators

	COBYX	BESIX	Difference
Max Drawdown Largest peak-to-trough decline	-34.18%	-38.05%	+3.87%
Max Drawdown (1Y) Largest decline over 1 year	-8.95%	-11.45%	+2.50%
Max Drawdown (3Y) Largest decline over 3 years	-16.29%	-21.34%	+5.05%
Max Drawdown (5Y) Largest decline over 5 years	-17.10%	-31.41%	+14.31%
Max Drawdown (10Y) Largest decline over 10 years	-34.18%	-38.05%	+3.87%
Current Drawdown Current decline from peak	-1.93%	-2.42%	+0.49%
Average Drawdown Average peak-to-trough decline	-6.80%	-10.19%	+3.39%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.99%	3.44%	-0.45%

Volatility

COBYX vs. BESIX - Volatility Comparison

The current volatility for The Cook & Bynum Fund (COBYX) is 3.71%, while William Blair Emerging Markets Small Cap Growth Fund (BESIX) has a volatility of 6.13%. This indicates that COBYX experiences smaller price fluctuations and is considered to be less risky than BESIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	COBYX	BESIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.71%	6.13%	-2.42%
Volatility (6M) Calculated over the trailing 6-month period	9.51%	14.87%	-5.36%
Volatility (1Y) Calculated over the trailing 1-year period	11.81%	17.88%	-6.07%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	13.99%	15.03%	-1.04%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	13.64%	16.24%	-2.60%

COBYX vs. BESIX - Expense Ratio Comparison

COBYX has a 1.49% expense ratio, which is higher than BESIX's 1.30% expense ratio.

Dividends

COBYX vs. BESIX - Dividend Comparison

COBYX's dividend yield for the trailing twelve months is around 1.07%, less than BESIX's 7.80% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
BESIX William Blair Emerging Markets Small Cap Growth Fund	7.80%	9.53%	0.00%	0.26%	4.84%	8.51%	0.04%	0.16%	2.32%	3.17%	2.67%	4.17%
COBYX The Cook & Bynum Fund	1.07%	1.18%	0.00%	1.01%	1.16%	2.18%	0.32%	0.69%	12.60%	1.88%	5.09%	0.00%

Frequently Asked Questions

Can I hold both COBYX and BESIX in my portfolio?

COBYX and BESIX have a correlation of 0.14, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, COBYX or BESIX?

BESIX has higher volatility (6.13%) compared to COBYX (3.71%). In terms of maximum drawdown, COBYX dropped -34.18% vs BESIX's -38.05%.

Which has better risk-adjusted returns?

BESIX currently has the higher Sharpe Ratio (2.44 vs 1.21), 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.