WBCIX vs. MOPIX

Last updated Jun 4, 2026

WBCIX (William Blair Small-Mid Cap Core Fund) and MOPIX (MainStay WMC Small Companies Fund) are both Small Cap Blend Equities funds. Over the past 5 years, WBCIX returned 5.31%/yr vs 9.07%/yr for MOPIX. Their correlation of 0.94 suggests significant overlap in exposure. WBCIX charges 1.25%/yr vs 0.97%/yr for MOPIX.

Performance

WBCIX vs. MOPIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in William Blair Small-Mid Cap Core Fund (WBCIX) and MainStay WMC Small Companies Fund (MOPIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, WBCIX achieves a 12.39% return, which is significantly lower than MOPIX's 27.70% return.

WBCIX

• 1D: 1.47%
• 1M: 5.78%
• YTD: 12.39%
• 6M: 12.52%
• 1Y: 21.24%
• 3Y*: 11.47%
• 5Y*: 5.31%
• 10Y*: —

MOPIX

• 1D: 0.76%
• 1M: 9.92%
• YTD: 27.70%
• 6M: 27.77%
• 1Y: 56.29%
• 3Y*: 23.19%
• 5Y*: 9.07%
• 10Y*: 9.35%

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

WBCIX vs. MOPIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019
WBCIX William Blair Small-Mid Cap Core Fund	12.39%	1.29%	12.04%	13.26%	-17.11%	26.63%	20.60%	10.29%
MOPIX MainStay WMC Small Companies Fund	27.70%	12.69%	16.07%	10.97%	-19.00%	17.55%	10.04%	11.69%

Correlation

The correlation between WBCIX and MOPIX is 0.91, 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	0.91
Correlation (3Y) Calculated over the trailing 3-year period	0.91
Correlation (5Y) Calculated over the trailing 5-year period	0.93
Correlation (All Time) Calculated using the full available price history since Oct 3, 2019	0.94

The correlation between WBCIX and MOPIX has been stable across timeframes, ranging from 0.91 to 0.94 - a consistent structural relationship.

Return for Risk

WBCIX vs. MOPIX — Risk / Return Rank

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

WBCIX

WBCIX Risk / Return Rank: 26
WBCIX Sharpe Ratio Rank: 22
WBCIX Sortino Ratio Rank: 23
WBCIX Omega Ratio Rank: 22
WBCIX Calmar Ratio Rank: 30
WBCIX Martin Ratio Rank: 32

MOPIX

MOPIX Risk / Return Rank: 91
MOPIX Sharpe Ratio Rank: 93
MOPIX Sortino Ratio Rank: 89
MOPIX Omega Ratio Rank: 80
MOPIX Calmar Ratio Rank: 96
MOPIX Martin Ratio Rank: 95

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.

WBCIX vs. MOPIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for William Blair Small-Mid Cap Core Fund (WBCIX) and MainStay WMC Small Companies Fund (MOPIX). 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.

	WBCIX	MOPIX	Difference
Sharpe ratio: Return per unit of total volatility	1.35	3.20	-1.85
Sortino ratio: Return per unit of downside risk	2.01	4.37	-2.36
Omega ratio: Gain probability vs. loss probability	1.24	1.53	-0.29
Calmar ratio: Return relative to maximum drawdown	2.06	6.08	-4.01
Martin ratio: Return relative to average drawdown	7.21	22.94	-15.73
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

WBCIX vs. MOPIX - Sharpe Ratio Comparison

The current WBCIX Sharpe Ratio is 1.35, which is lower than the MOPIX Sharpe Ratio of 3.20. The chart below compares the historical Sharpe Ratios of WBCIX and MOPIX, 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

	WBCIX	MOPIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.35	3.20	-1.85
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.26	0.40	-0.14
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	0.40	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.47	0.49	-0.02

Drawdowns

WBCIX vs. MOPIX - Drawdown Comparison

The maximum WBCIX drawdown since its inception was -39.56%, smaller than the maximum MOPIX drawdown of -68.08%. Use the drawdown chart below to compare losses from any high point for WBCIX and MOPIX.

Drawdown Indicators

	WBCIX	MOPIX	Difference
Max Drawdown Largest peak-to-trough decline	-39.56%	-68.08%	+28.52%
Max Drawdown (1Y) Largest decline over 1 year	-11.06%	-9.84%	-1.22%
Max Drawdown (3Y) Largest decline over 3 years	-23.53%	-26.99%	+3.46%
Max Drawdown (5Y) Largest decline over 5 years	-27.65%	-32.60%	+4.95%
Max Drawdown (10Y) Largest decline over 10 years	—	-48.01%	—
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-9.14%	-9.11%	-0.03%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.15%	2.60%	+0.55%

Volatility

WBCIX vs. MOPIX - Volatility Comparison

The current volatility for William Blair Small-Mid Cap Core Fund (WBCIX) is 5.07%, while MainStay WMC Small Companies Fund (MOPIX) has a volatility of 5.92%. This indicates that WBCIX experiences smaller price fluctuations and is considered to be less risky than MOPIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	WBCIX	MOPIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.07%	5.92%	-0.85%
Volatility (6M) Calculated over the trailing 6-month period	12.55%	13.71%	-1.16%
Volatility (1Y) Calculated over the trailing 1-year period	16.87%	18.68%	-1.81%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	20.70%	22.81%	-2.11%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	23.82%	23.38%	+0.44%

WBCIX vs. MOPIX - Expense Ratio Comparison

WBCIX has a 1.25% expense ratio, which is higher than MOPIX's 0.97% expense ratio.

Dividends

WBCIX vs. MOPIX - Dividend Comparison

WBCIX's dividend yield for the trailing twelve months is around 2.66%, more than MOPIX's 0.12% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
MOPIX MainStay WMC Small Companies Fund	0.12%	0.15%	0.39%	0.33%	2.34%	29.42%	0.00%	0.50%	18.09%	8.32%	0.59%	0.37%
WBCIX William Blair Small-Mid Cap Core Fund	2.66%	2.98%	1.35%	0.15%	0.00%	0.00%	0.00%	0.06%	0.00%	0.00%	0.00%	0.00%

Frequently Asked Questions

Can I hold both WBCIX and MOPIX in my portfolio?

With a correlation of 0.91, WBCIX and MOPIX 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, WBCIX or MOPIX?

MOPIX has higher volatility (5.92%) compared to WBCIX (5.07%). In terms of maximum drawdown, WBCIX dropped -39.56% vs MOPIX's -68.08%.

Which has better risk-adjusted returns?

MOPIX currently has the higher Sharpe Ratio (3.20 vs 1.35), 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.