WSMDX vs. FZFLX

Last updated Jul 25, 2026

WSMDX (William Blair Small-Mid Cap Growth Fund) and FZFLX (Fidelity SAI Small-Mid Cap 500 Index Fund) are both mutual funds - WSMDX is a Mid Cap Growth Equities fund managed by William Blair, while FZFLX is a Mid Cap Blend Equities fund managed by Fidelity. Over the past 10 years, WSMDX returned 11.95%/yr vs 13.44%/yr for FZFLX. Their correlation of 0.92 means they have usually moved in the same direction. WSMDX charges 1.10%/yr vs 0.05%/yr for FZFLX.

Performance

WSMDX vs. FZFLX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in William Blair Small-Mid Cap Growth Fund (WSMDX) and Fidelity SAI Small-Mid Cap 500 Index Fund (FZFLX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, WSMDX achieves a 10.43% return, which is significantly lower than FZFLX's 30.13% return. Over the past 10 years, WSMDX has underperformed FZFLX with an annualized return of 11.95%, while FZFLX has yielded a comparatively higher 13.44% annualized return.

WSMDX

• 1D: -0.36%
• 1M: -2.67%
• 6M: 5.25%
• YTD: 10.43%
• 1Y: 15.57%
• 3Y*: 13.98%
• 5Y*: 5.26%
• 10Y*: 11.95%
• ALL TIME*: 11.44%

FZFLX

• 1D: -0.51%
• 1M: -3.16%
• 6M: 19.96%
• YTD: 30.13%
• 1Y: 35.43%
• 3Y*: 20.32%
• 5Y*: 11.56%
• 10Y*: 13.44%
• ALL TIME*: 12.74%

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

Liquidity Comparison

Position	Avg. Volume Value (2W)	Avg. Volume Value (1M)	Avg. Volume Value (3M)
FZFLX Fidelity SAI Small-Mid Cap 500 Index Fund	$0.00	$0.00	$0.00
WSMDX William Blair Small-Mid Cap Growth Fund	$0.00	$0.00	$0.00

WSMDX vs. FZFLX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
WSMDX William Blair Small-Mid Cap Growth Fund	10.43%	0.63%	27.55%	18.14%	-22.98%	8.28%	32.38%	30.81%	-2.18%	28.85%
FZFLX Fidelity SAI Small-Mid Cap 500 Index Fund	30.13%	10.76%	15.52%	17.75%	-15.62%	20.40%	19.78%	31.96%	-9.25%	18.41%

Correlation

The correlation between WSMDX and FZFLX is 0.89, meaning they have usually moved in the same direction, including during past declines.

	Correlation
Correlation (1Y) Focuses on recent behavior, but can change the most.	0.89
Correlation (3Y) Balances recent behavior with more history.	0.91
Correlation (5Y) Shows whether the relationship held over a longer period.	0.93
Correlation (10Y) Provides a long-term view across more market conditions.	0.91
Correlation (All Time) Calculated using the full available price history since Aug 20, 2015	0.92

The correlation between WSMDX and FZFLX has been stable across timeframes, ranging from 0.89 to 0.93 - a consistent structural relationship.

Return for Risk

WSMDX vs. FZFLX — Risk / Return Rank

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

WSMDX

WSMDX Risk / Return Rank: 26
WSMDX Sharpe Ratio Rank: 22
WSMDX Sortino Ratio Rank: 24
WSMDX Omega Ratio Rank: 22
WSMDX Calmar Ratio Rank: 30
WSMDX Martin Ratio Rank: 33

FZFLX

FZFLX Risk / Return Rank: 69
FZFLX Sharpe Ratio Rank: 59
FZFLX Sortino Ratio Rank: 56
FZFLX Omega Ratio Rank: 55
FZFLX Calmar Ratio Rank: 88
FZFLX Martin Ratio Rank: 87

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.

WSMDX vs. FZFLX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for William Blair Small-Mid Cap Growth Fund (WSMDX) and Fidelity SAI Small-Mid Cap 500 Index Fund (FZFLX). 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.

	WSMDX	FZFLX	Difference
Sharpe ratio: Return per unit of total volatility	0.86	1.58	-0.72
Sortino ratio: Return per unit of downside risk	1.32	2.21	-0.88
Omega ratio: Gain probability vs. loss probability	1.15	1.28	-0.12
Calmar ratio: Return relative to maximum drawdown	1.43	3.33	-1.90
Martin ratio: Return relative to average drawdown	5.06	11.99	-6.93

WSMDX vs. FZFLX - Sharpe Ratio Comparison

The current WSMDX Sharpe Ratio is 0.86, which is lower than the FZFLX Sharpe Ratio of 1.58. The chart below compares the historical Sharpe Ratios of WSMDX and FZFLX, 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

WSMDX vs. FZFLX - Drawdown Comparison

The maximum WSMDX drawdown since its inception was -50.33%, which is greater than FZFLX's maximum drawdown of -42.03%. Use the drawdown chart below to compare losses from any high point for WSMDX and FZFLX.

Drawdown Indicators

	WSMDX	FZFLX	Difference
Max Drawdown Largest peak-to-trough decline	-50.33%	-42.03%	-8.30%
Max Drawdown (1Y) Largest decline over 1 year	-11.50%	-10.68%	-0.82%
Max Drawdown (3Y) Largest decline over 3 years	-25.63%	-22.29%	-3.34%
Max Drawdown (5Y) Largest decline over 5 years	-36.89%	-24.77%	-12.12%
Max Drawdown (10Y) Largest decline over 10 years	-36.89%	-42.03%	+5.14%
Current Drawdown Current decline from peak	-4.36%	-5.51%	+1.15%
Average Drawdown Average peak-to-trough decline	-8.42%	-5.71%	-2.71%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.23%	2.96%	+0.27%

Volatility

WSMDX vs. FZFLX - Volatility Comparison

The current volatility for William Blair Small-Mid Cap Growth Fund (WSMDX) is 4.49%, while Fidelity SAI Small-Mid Cap 500 Index Fund (FZFLX) has a volatility of 6.85%. This indicates that WSMDX experiences smaller price fluctuations and is considered to be less risky than FZFLX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	WSMDX	FZFLX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.49%	6.85%	-2.36%
Volatility (6M) Calculated over the trailing 6-month period	15.03%	19.49%	-4.46%
Volatility (1Y) Calculated over the trailing 1-year period	19.18%	22.53%	-3.35%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	23.17%	21.40%	+1.77%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	21.95%	21.21%	+0.74%

WSMDX vs. FZFLX - Expense Ratio Comparison

WSMDX has a 1.10% expense ratio, which is higher than FZFLX's 0.05% expense ratio.

Dividends

WSMDX vs. FZFLX - Dividend Comparison

WSMDX's dividend yield for the trailing twelve months is around 2.54%, less than FZFLX's 44.39% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FZFLX Fidelity SAI Small-Mid Cap 500 Index Fund	44.39%	57.77%	10.20%	2.35%	79.79%	50.77%	7.19%	6.49%	7.69%	1.68%	0.93%	0.67%
WSMDX William Blair Small-Mid Cap Growth Fund	2.54%	2.81%	24.90%	7.89%	3.34%	9.30%	1.66%	7.13%	8.88%	5.33%	2.64%	5.31%

Frequently Asked Questions

Can I hold both WSMDX and FZFLX in my portfolio?

WSMDX and FZFLX have a correlation of 0.89, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, WSMDX or FZFLX?

FZFLX has higher volatility (6.85%) compared to WSMDX (4.49%). In terms of maximum drawdown, WSMDX dropped -50.33% vs FZFLX's -42.03%.

Which has better risk-adjusted returns?

FZFLX currently has the higher Sharpe Ratio (1.58 vs 0.86), 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.