RCKSX vs. PRBLX
RCKSX (Rock Oak Core Growth Fund) and PRBLX (Parnassus Core Equity Fund Investor Shares) are both Large Cap Blend Equities funds. Over the past 10 years, RCKSX returned 11.23%/yr vs 13.50%/yr for PRBLX. Their correlation of 0.84 means they have usually moved in the same direction. RCKSX charges 1.25%/yr vs 0.81%/yr for PRBLX.
Performance
RCKSX vs. PRBLX - Performance Comparison
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Returns By Period
In the year-to-date period, RCKSX achieves a 20.84% return, which is significantly higher than PRBLX's 7.76% return. Over the past 10 years, RCKSX has underperformed PRBLX with an annualized return of 11.23%, while PRBLX has yielded a comparatively higher 13.50% annualized return.
RCKSX
- 1D
- 0.49%
- 1M
- 1.77%
- 6M
- 14.90%
- YTD
- 20.84%
- 1Y
- 26.97%
- 3Y*
- 19.18%
- 5Y*
- 8.92%
- 10Y*
- 11.23%
- ALL TIME*
- 8.00%
PRBLX
- 1D
- 1.79%
- 1M
- -0.84%
- 6M
- 6.19%
- YTD
- 7.76%
- 1Y
- 11.73%
- 3Y*
- 14.28%
- 5Y*
- 9.28%
- 10Y*
- 13.50%
- ALL TIME*
- 11.23%
Liquidity Comparison
| Position | Avg. Volume Value (2W) | Avg. Volume Value (1M) | Avg. Volume Value (3M) |
|---|---|---|---|
| $0.00 | $0.00 | $0.00 | |
| $0.00 | $0.00 | $0.00 |
RCKSX vs. PRBLX - Yearly Performance Comparison
| 2026 (YTD) | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | |
|---|---|---|---|---|---|---|---|---|---|---|
RCKSX Rock Oak Core Growth Fund | 20.84% | 12.99% | 15.12% | 15.57% | -18.09% | 9.96% | 13.75% | 19.05% | -2.14% | 22.69% |
PRBLX Parnassus Core Equity Fund Investor Shares | 7.76% | 11.67% | 18.58% | 24.97% | -18.64% | 27.59% | 21.21% | 30.68% | -0.30% | 16.63% |
Correlation
The correlation between RCKSX and PRBLX is 0.62, which is moderate. They have sometimes moved together and sometimes differently, sharing some price drivers without tracking each other closely.
| Correlation | |
|---|---|
Correlation (1Y) Focuses on recent behavior, but can change the most. | 0.62 |
Correlation (3Y) Balances recent behavior with more history. | 0.71 |
Correlation (5Y) Shows whether the relationship held over a longer period. | 0.79 |
Correlation (10Y) Provides a long-term view across more market conditions. | 0.80 |
Correlation (All Time) Calculated using the full available price history since Jan 3, 2005 | 0.84 |
Over the past year, the correlation between RCKSX and PRBLX has dropped to 0.62 - well below their long-term average of 0.84, suggesting their price drivers have been diverging.
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Return for Risk
RCKSX vs. PRBLX — Risk / Return Rank
RCKSX
PRBLX
RCKSX vs. PRBLX - Risk-Adjusted Trends Comparison
This table presents a comparison of risk-adjusted performance metrics for Rock Oak Core Growth Fund (RCKSX) and Parnassus Core Equity Fund Investor Shares (PRBLX). 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.
| RCKSX | PRBLX | Difference | |
|---|---|---|---|
| Sharpe ratioReturn per unit of total volatility | +1.43 | ||
| Sortino ratioReturn per unit of downside risk | +1.99 | ||
| Omega ratioGain probability vs. loss probability | 1.36 | 1.13 | +0.23 |
| Calmar ratioReturn relative to maximum drawdown | 5.87 | 0.79 | +5.08 |
| Martin ratioReturn relative to average drawdown | 19.20 | 3.05 | +16.15 |
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Drawdowns
RCKSX vs. PRBLX - Drawdown Comparison
The maximum RCKSX drawdown since its inception was -57.88%, which is greater than PRBLX's maximum drawdown of -42.20%. Use the drawdown chart below to compare losses from any high point for RCKSX and PRBLX.
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Drawdown Indicators
| RCKSX | PRBLX | Difference | |
|---|---|---|---|
Max DrawdownLargest peak-to-trough decline | -57.88% | -42.20% | -15.68% |
Max Drawdown (1Y)Largest decline over 1 year | -4.14% | -11.63% | +7.49% |
Max Drawdown (3Y)Largest decline over 3 years | -18.22% | -16.31% | -1.91% |
Max Drawdown (5Y)Largest decline over 5 years | -22.54% | -26.31% | +3.77% |
Max Drawdown (10Y)Largest decline over 10 years | -33.10% | -30.09% | -3.01% |
Current DrawdownCurrent decline from peak | -0.28% | -1.70% | +1.42% |
Average DrawdownAverage peak-to-trough decline | -9.44% | -4.03% | -5.41% |
Ulcer IndexDepth and duration of drawdowns from previous peaks | 1.28% | 3.03% | -1.75% |
Volatility
RCKSX vs. PRBLX - Volatility Comparison
The current volatility for Rock Oak Core Growth Fund (RCKSX) is 2.54%, while Parnassus Core Equity Fund Investor Shares (PRBLX) has a volatility of 3.70%. This indicates that RCKSX experiences smaller price fluctuations and is considered to be less risky than PRBLX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.
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Volatility by Period
| RCKSX | PRBLX | Difference | |
|---|---|---|---|
Volatility (1M)Calculated over the trailing 1-month period | 2.54% | 3.70% | -1.16% |
Volatility (6M)Calculated over the trailing 6-month period | 7.57% | 10.38% | -2.81% |
Volatility (1Y)Calculated over the trailing 1-year period | 11.36% | 12.90% | -1.54% |
Volatility (5Y)Calculated over the trailing 5-year period, annualized | 15.57% | 16.40% | -0.83% |
Volatility (10Y)Calculated over the trailing 10-year period, annualized | 17.39% | 17.28% | +0.11% |
RCKSX vs. PRBLX - Expense Ratio Comparison
RCKSX has a 1.25% expense ratio, which is higher than PRBLX's 0.81% expense ratio.
Dividends
RCKSX vs. PRBLX - Dividend Comparison
RCKSX's dividend yield for the trailing twelve months is around 5.18%, less than PRBLX's 17.66% yield.
| Position | TTM | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | 2015 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
PRBLX Parnassus Core Equity Fund Investor Shares | 17.66% | 19.08% | 10.00% | 6.01% | 10.13% | 7.77% | 5.87% | 8.02% | 9.64% | 7.16% | 3.80% | 9.62% |
RCKSX Rock Oak Core Growth Fund | 5.18% | 6.26% | 0.47% | 0.71% | 1.00% | 4.31% | 16.56% | 3.18% | 0.59% | 5.91% | 0.70% | 3.21% |
Frequently Asked Questions
RCKSX and PRBLX have a correlation of 0.62, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.
PRBLX has higher volatility (3.70%) compared to RCKSX (2.54%). In terms of maximum drawdown, RCKSX dropped -57.88% vs PRBLX's -42.20%.
RCKSX currently has the higher Sharpe Ratio (2.14 vs 0.71), 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.
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