OSTFX vs. FSKAX

Last updated Jun 24, 2026

OSTFX (Osterweis Fund) and FSKAX (Fidelity Total Market Index Fund) are both Large Cap Blend Equities funds. Over the past 10 years, OSTFX returned 12.08%/yr vs 15.27%/yr for FSKAX. Their correlation of 0.94 suggests significant overlap in exposure. OSTFX charges 0.95%/yr vs 0.01%/yr for FSKAX.

Performance

OSTFX vs. FSKAX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Osterweis Fund (OSTFX) and Fidelity Total Market Index Fund (FSKAX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, OSTFX achieves a 4.18% return, which is significantly lower than FSKAX's 10.43% return. Over the past 10 years, OSTFX has underperformed FSKAX with an annualized return of 12.08%, while FSKAX has yielded a comparatively higher 15.27% annualized return.

OSTFX

• 1D: -0.67%
• 1M: -0.53%
• YTD: 4.18%
• 6M: 3.29%
• 1Y: 15.34%
• 3Y*: 14.30%
• 5Y*: 7.20%
• 10Y*: 12.08%

FSKAX

• 1D: -0.34%
• 1M: 0.56%
• YTD: 10.43%
• 6M: 9.28%
• 1Y: 25.95%
• 3Y*: 21.24%
• 5Y*: 12.40%
• 10Y*: 15.27%

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

OSTFX vs. FSKAX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
OSTFX Osterweis Fund	4.18%	12.85%	13.48%	22.64%	-22.01%	22.58%	23.20%	43.39%	-7.85%	14.82%
FSKAX Fidelity Total Market Index Fund	10.43%	17.06%	23.89%	26.12%	-19.53%	25.66%	20.79%	30.92%	-5.32%	20.85%

Correlation

The correlation between OSTFX and FSKAX 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	0.92
Correlation (5Y) Calculated over the trailing 5-year period	0.95
Correlation (10Y) Calculated over the trailing 10-year period	0.94
Correlation (All Time) Calculated using the full available price history since Sep 8, 2011	0.94

The correlation between OSTFX and FSKAX has been stable across timeframes, ranging from 0.91 to 0.95 - a consistent structural relationship.

Return for Risk

OSTFX vs. FSKAX — Risk / Return Rank

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

OSTFX

OSTFX Risk / Return Rank: 28
OSTFX Sharpe Ratio Rank: 28
OSTFX Sortino Ratio Rank: 28
OSTFX Omega Ratio Rank: 26
OSTFX Calmar Ratio Rank: 23
OSTFX Martin Ratio Rank: 33

FSKAX

FSKAX Risk / Return Rank: 64
FSKAX Sharpe Ratio Rank: 61
FSKAX Sortino Ratio Rank: 55
FSKAX Omega Ratio Rank: 56
FSKAX Calmar Ratio Rank: 70
FSKAX Martin Ratio Rank: 78

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.

OSTFX vs. FSKAX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Osterweis Fund (OSTFX) and Fidelity Total Market Index Fund (FSKAX). 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.

	OSTFX	FSKAX	Difference
Sharpe ratio: Return per unit of total volatility	1.39	2.12	-0.73
Sortino ratio: Return per unit of downside risk	2.03	2.87	-0.84
Omega ratio: Gain probability vs. loss probability	1.24	1.38	-0.14
Calmar ratio: Return relative to maximum drawdown	1.63	3.06	-1.43
Martin ratio: Return relative to average drawdown	7.08	13.62	-6.53

OSTFX vs. FSKAX - Sharpe Ratio Comparison

The current OSTFX Sharpe Ratio is 1.39, which is lower than the FSKAX Sharpe Ratio of 2.12. The chart below compares the historical Sharpe Ratios of OSTFX and FSKAX, 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

OSTFX vs. FSKAX - Drawdown Comparison

The maximum OSTFX drawdown since its inception was -40.63%, which is greater than FSKAX's maximum drawdown of -35.01%. Use the drawdown chart below to compare losses from any high point for OSTFX and FSKAX.

Drawdown Indicators

	OSTFX	FSKAX	Difference
Max Drawdown Largest peak-to-trough decline	-40.63%	-35.01%	-5.62%
Max Drawdown (1Y) Largest decline over 1 year	-10.06%	-8.92%	-1.14%
Max Drawdown (3Y) Largest decline over 3 years	-15.80%	-19.43%	+3.63%
Max Drawdown (5Y) Largest decline over 5 years	-27.62%	-25.39%	-2.23%
Max Drawdown (10Y) Largest decline over 10 years	-32.54%	-35.01%	+2.47%
Current Drawdown Current decline from peak	-1.52%	-1.47%	-0.05%
Average Drawdown Average peak-to-trough decline	-6.83%	-4.01%	-2.82%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.31%	2.00%	+0.31%

Volatility

OSTFX vs. FSKAX - Volatility Comparison

The current volatility for Osterweis Fund (OSTFX) is 3.53%, while Fidelity Total Market Index Fund (FSKAX) has a volatility of 4.80%. This indicates that OSTFX experiences smaller price fluctuations and is considered to be less risky than FSKAX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	OSTFX	FSKAX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.53%	4.80%	-1.27%
Volatility (6M) Calculated over the trailing 6-month period	9.18%	10.10%	-0.92%
Volatility (1Y) Calculated over the trailing 1-year period	11.83%	12.91%	-1.08%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	15.67%	17.50%	-1.83%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	16.84%	18.50%	-1.66%

OSTFX vs. FSKAX - Expense Ratio Comparison

OSTFX has a 0.95% expense ratio, which is higher than FSKAX's 0.02% expense ratio.

Dividends

OSTFX vs. FSKAX - Dividend Comparison

OSTFX's dividend yield for the trailing twelve months is around 5.74%, more than FSKAX's 0.95% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FSKAX Fidelity Total Market Index Fund	0.95%	1.01%	1.19%	1.41%	1.62%	1.15%	1.45%	1.94%	2.54%	2.07%	2.43%	0.82%
OSTFX Osterweis Fund	5.74%	5.98%	14.93%	4.01%	7.81%	12.83%	5.48%	14.46%	29.80%	43.97%	7.35%	22.55%

Frequently Asked Questions

Can I hold both OSTFX and FSKAX in my portfolio?

With a correlation of 0.91, OSTFX and FSKAX 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, OSTFX or FSKAX?

FSKAX has higher volatility (4.80%) compared to OSTFX (3.53%). In terms of maximum drawdown, OSTFX dropped -40.63% vs FSKAX's -35.01%.

Which has better risk-adjusted returns?

FSKAX currently has the higher Sharpe Ratio (2.12 vs 1.39), 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.