OBSOX vs. FSSNX

Last updated Jun 4, 2026

OBSOX (Oberweis Small-Cap Opportunities Fund) and FSSNX (Fidelity Small Cap Index Fund) are both mutual funds - OBSOX is a Small Cap Growth Equities fund managed by Oberweis, while FSSNX is a Small Cap Blend Equities fund managed by Fidelity. Over the past 10 years, OBSOX returned 19.01%/yr vs 11.22%/yr for FSSNX. Their correlation of 0.91 suggests significant overlap in exposure. OBSOX charges 1.25%/yr vs 0.03%/yr for FSSNX.

Performance

OBSOX vs. FSSNX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Oberweis Small-Cap Opportunities Fund (OBSOX) and Fidelity Small Cap Index Fund (FSSNX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, OBSOX achieves a 36.53% return, which is significantly higher than FSSNX's 18.72% return. Over the past 10 years, OBSOX has outperformed FSSNX with an annualized return of 19.01%, while FSSNX has yielded a comparatively lower 11.22% annualized return.

OBSOX

• 1D: 2.92%
• 1M: 8.39%
• YTD: 36.53%
• 6M: 35.36%
• 1Y: 60.95%
• 3Y*: 24.06%
• 5Y*: 17.06%
• 10Y*: 19.01%

FSSNX

• 1D: 0.91%
• 1M: 4.97%
• YTD: 18.72%
• 6M: 17.45%
• 1Y: 41.33%
• 3Y*: 18.75%
• 5Y*: 6.72%
• 10Y*: 11.22%

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

OBSOX vs. FSSNX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
OBSOX Oberweis Small-Cap Opportunities Fund	36.53%	14.28%	16.13%	15.81%	-11.17%	43.39%	32.52%	25.06%	-7.05%	25.55%
FSSNX Fidelity Small Cap Index Fund	18.72%	12.94%	11.71%	17.11%	-20.28%	14.70%	19.99%	25.70%	-11.24%	14.54%

Correlation

The correlation between OBSOX and FSSNX is 0.80, 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	0.80
Correlation (3Y) Calculated over the trailing 3-year period	0.86
Correlation (5Y) Calculated over the trailing 5-year period	0.90
Correlation (10Y) Calculated over the trailing 10-year period	0.90
Correlation (All Time) Calculated using the full available price history since Sep 12, 2011	0.91

The correlation between OBSOX and FSSNX shifts across timeframes, from 0.80 (1 year) to 0.91 (all time), reflecting how their relationship changes across market environments.

Return for Risk

OBSOX vs. FSSNX — Risk / Return Rank

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

OBSOX

OBSOX Risk / Return Rank: 75
OBSOX Sharpe Ratio Rank: 75
OBSOX Sortino Ratio Rank: 57
OBSOX Omega Ratio Rank: 55
OBSOX Calmar Ratio Rank: 94
OBSOX Martin Ratio Rank: 94

FSSNX

FSSNX Risk / Return Rank: 64
FSSNX Sharpe Ratio Rank: 61
FSSNX Sortino Ratio Rank: 55
FSSNX Omega Ratio Rank: 47
FSSNX Calmar Ratio Rank: 85
FSSNX Martin Ratio Rank: 74

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.

OBSOX vs. FSSNX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Oberweis Small-Cap Opportunities Fund (OBSOX) and Fidelity Small Cap Index Fund (FSSNX). 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.

	OBSOX	FSSNX	Difference
Sharpe ratio: Return per unit of total volatility	2.51	2.29	+0.23
Sortino ratio: Return per unit of downside risk	3.18	3.14	+0.04
Omega ratio: Gain probability vs. loss probability	1.41	1.37	+0.04
Calmar ratio: Return relative to maximum drawdown	5.64	3.98	+1.66
Martin ratio: Return relative to average drawdown	20.82	14.13	+6.68
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

OBSOX vs. FSSNX - Sharpe Ratio Comparison

The current OBSOX Sharpe Ratio is 2.51, which is comparable to the FSSNX Sharpe Ratio of 2.29. The chart below compares the historical Sharpe Ratios of OBSOX and FSSNX, 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

	OBSOX	FSSNX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.51	2.29	+0.23
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.68	0.30	+0.39
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.77	0.48	+0.29
Sharpe Ratio (All Time) Calculated using the full available price history	0.33	0.54	-0.20

Drawdowns

OBSOX vs. FSSNX - Drawdown Comparison

The maximum OBSOX drawdown since its inception was -80.52%, which is greater than FSSNX's maximum drawdown of -41.72%. Use the drawdown chart below to compare losses from any high point for OBSOX and FSSNX.

Drawdown Indicators

	OBSOX	FSSNX	Difference
Max Drawdown Largest peak-to-trough decline	-80.52%	-41.72%	-38.80%
Max Drawdown (1Y) Largest decline over 1 year	-11.40%	-11.00%	-0.40%
Max Drawdown (3Y) Largest decline over 3 years	-27.74%	-27.45%	-0.29%
Max Drawdown (5Y) Largest decline over 5 years	-28.65%	-31.87%	+3.22%
Max Drawdown (10Y) Largest decline over 10 years	-42.79%	-41.72%	-1.07%
Current Drawdown Current decline from peak	0.00%	-0.14%	+0.14%
Average Drawdown Average peak-to-trough decline	-30.55%	-8.29%	-22.26%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.07%	3.09%	-0.02%

Volatility

OBSOX vs. FSSNX - Volatility Comparison

Oberweis Small-Cap Opportunities Fund (OBSOX) has a higher volatility of 8.92% compared to Fidelity Small Cap Index Fund (FSSNX) at 5.59%. This indicates that OBSOX's price experiences larger fluctuations and is considered to be riskier than FSSNX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	OBSOX	FSSNX	Difference
Volatility (1M) Calculated over the trailing 1-month period	8.92%	5.59%	+3.33%
Volatility (6M) Calculated over the trailing 6-month period	20.40%	13.59%	+6.81%
Volatility (1Y) Calculated over the trailing 1-year period	25.56%	19.13%	+6.43%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	25.07%	22.58%	+2.49%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	24.77%	23.45%	+1.32%

OBSOX vs. FSSNX - Expense Ratio Comparison

OBSOX has a 1.25% expense ratio, which is higher than FSSNX's 0.03% expense ratio.

Dividends

OBSOX vs. FSSNX - Dividend Comparison

OBSOX has not paid dividends to shareholders, while FSSNX's dividend yield for the trailing twelve months is around 0.91%.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FSSNX Fidelity Small Cap Index Fund	0.91%	1.08%	1.04%	1.43%	1.26%	3.92%	0.94%	2.96%	4.94%	3.37%	2.27%	2.66%
OBSOX Oberweis Small-Cap Opportunities Fund	0.00%	0.00%	0.80%	0.00%	0.17%	21.88%	4.05%	3.04%	28.22%	6.36%	4.24%	11.91%

Frequently Asked Questions

Can I hold both OBSOX and FSSNX in my portfolio?

OBSOX and FSSNX have a correlation of 0.80, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, OBSOX or FSSNX?

OBSOX has higher volatility (8.92%) compared to FSSNX (5.59%). In terms of maximum drawdown, OBSOX dropped -80.52% vs FSSNX's -41.72%.

Which has better risk-adjusted returns?

OBSOX currently has the higher Sharpe Ratio (2.51 vs 2.29), 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.