FZFLX vs. WSMDX

Last updated Jun 3, 2026

FZFLX (Fidelity SAI Small-Mid Cap 500 Index Fund) and WSMDX (William Blair Small-Mid Cap Growth Fund) are both mutual funds - FZFLX is a Mid Cap Blend Equities fund managed by Fidelity, while WSMDX is a Mid Cap Growth Equities fund managed by William Blair. Over the past 10 years, FZFLX returned 13.89%/yr vs 12.41%/yr for WSMDX. Their correlation of 0.92 suggests significant overlap in exposure. FZFLX charges 0.05%/yr vs 1.10%/yr for WSMDX.

Performance

FZFLX vs. WSMDX - Performance Comparison

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

Returns By Period

In the year-to-date period, FZFLX achieves a 31.03% return, which is significantly higher than WSMDX's 11.78% return. Over the past 10 years, FZFLX has outperformed WSMDX with an annualized return of 13.89%, while WSMDX has yielded a comparatively lower 12.41% annualized return.

FZFLX

• 1D: -0.68%
• 1M: 4.45%
• YTD: 31.03%
• 6M: 32.60%
• 1Y: 48.15%
• 3Y*: 23.77%
• 5Y*: 11.54%
• 10Y*: 13.89%

WSMDX

• 1D: 0.13%
• 1M: 3.97%
• YTD: 11.78%
• 6M: 11.21%
• 1Y: 25.91%
• 3Y*: 16.52%
• 5Y*: 6.34%
• 10Y*: 12.41%

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

FZFLX vs. WSMDX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
FZFLX Fidelity SAI Small-Mid Cap 500 Index Fund	31.03%	10.76%	15.52%	17.75%	-15.62%	20.40%	19.78%	31.96%	-9.25%	18.41%
WSMDX William Blair Small-Mid Cap Growth Fund	11.78%	0.63%	27.55%	18.14%	-22.98%	8.28%	32.38%	30.81%	-2.18%	28.85%

Correlation

The correlation between FZFLX and WSMDX is 0.89, 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	0.89
Correlation (3Y) Calculated over the trailing 3-year period	0.91
Correlation (5Y) Calculated over the trailing 5-year period	0.92
Correlation (10Y) Calculated over the trailing 10-year period	0.91
Correlation (All Time) Calculated using the full available price history since Aug 21, 2015	0.92

The correlation between FZFLX and WSMDX has been stable across timeframes, ranging from 0.89 to 0.92 - a consistent structural relationship.

Return for Risk

FZFLX vs. WSMDX — Risk / Return Rank

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

FZFLX

FZFLX Risk / Return Rank: 70
FZFLX Sharpe Ratio Rank: 62
FZFLX Sortino Ratio Rank: 54
FZFLX Omega Ratio Rank: 53
FZFLX Calmar Ratio Rank: 89
FZFLX Martin Ratio Rank: 91

WSMDX

WSMDX Risk / Return Rank: 29
WSMDX Sharpe Ratio Rank: 25
WSMDX Sortino Ratio Rank: 25
WSMDX Omega Ratio Rank: 22
WSMDX Calmar Ratio Rank: 36
WSMDX Martin Ratio Rank: 39

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.

FZFLX vs. WSMDX - Risk-Adjusted Trends Comparison

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

	FZFLX	WSMDX	Difference
Sharpe ratio Return per unit of total volatility	2.33	1.46	+0.87
Sortino ratio Return per unit of downside risk	3.09	2.11	+0.98
Omega ratio Gain probability vs. loss probability	1.41	1.25	+0.15
Calmar ratio Return relative to maximum drawdown	4.49	2.30	+2.18
Martin ratio Return relative to average drawdown	19.03	8.53	+10.50
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FZFLX vs. WSMDX - Sharpe Ratio Comparison

The current FZFLX Sharpe Ratio is 2.33, which is higher than the WSMDX Sharpe Ratio of 1.46. The chart below compares the historical Sharpe Ratios of FZFLX and WSMDX, 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

	FZFLX	WSMDX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.33	1.46	+0.87
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.55	0.28	+0.27
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.66	0.57	+0.09
Sharpe Ratio (All Time) Calculated using the full available price history	0.62	0.54	+0.08

Drawdowns

FZFLX vs. WSMDX - Drawdown Comparison

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

Drawdown Indicators

	FZFLX	WSMDX	Difference
Max Drawdown Largest peak-to-trough decline	-42.03%	-50.33%	+8.30%
Max Drawdown (1Y) Largest decline over 1 year	-10.68%	-11.50%	+0.82%
Max Drawdown (3Y) Largest decline over 3 years	-22.29%	-25.63%	+3.34%
Max Drawdown (5Y) Largest decline over 5 years	-24.77%	-36.89%	+12.12%
Max Drawdown (10Y) Largest decline over 10 years	-42.03%	-36.89%	-5.14%
Current Drawdown Current decline from peak	-1.84%	0.00%	-1.84%
Average Drawdown Average peak-to-trough decline	-5.74%	-8.46%	+2.72%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.52%	3.11%	-0.59%

Volatility

FZFLX vs. WSMDX - Volatility Comparison

Fidelity SAI Small-Mid Cap 500 Index Fund (FZFLX) has a higher volatility of 7.30% compared to William Blair Small-Mid Cap Growth Fund (WSMDX) at 5.45%. This indicates that FZFLX's price experiences larger fluctuations and is considered to be riskier than WSMDX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FZFLX	WSMDX	Difference
Volatility (1M) Calculated over the trailing 1-month period	7.30%	5.45%	+1.85%
Volatility (6M) Calculated over the trailing 6-month period	17.66%	14.13%	+3.53%
Volatility (1Y) Calculated over the trailing 1-year period	20.84%	18.27%	+2.57%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	21.10%	23.04%	-1.94%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	21.10%	21.94%	-0.84%

FZFLX vs. WSMDX - Expense Ratio Comparison

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

Dividends

FZFLX vs. WSMDX - Dividend Comparison

FZFLX's dividend yield for the trailing twelve months is around 44.09%, more than WSMDX's 2.51% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FZFLX Fidelity SAI Small-Mid Cap 500 Index Fund	44.09%	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	2.51%	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 FZFLX and WSMDX in my portfolio?

FZFLX and WSMDX 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, FZFLX or WSMDX?

FZFLX has higher volatility (7.30%) compared to WSMDX (5.45%). In terms of maximum drawdown, FZFLX dropped -42.03% vs WSMDX's -50.33%.

Which has better risk-adjusted returns?

FZFLX currently has the higher Sharpe Ratio (2.33 vs 1.46), 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.