PRBLX vs. NOSIX

Last updated Aug 1, 2026

PRBLX (Parnassus Core Equity Fund Investor Shares) and NOSIX (Northern Stock Index Fund) are both Large Cap Blend Equities funds. Over the past 10 years, PRBLX returned 13.50%/yr vs 14.90%/yr for NOSIX. Their correlation of 0.89 means they have usually moved in the same direction. PRBLX charges 0.81%/yr vs 0.05%/yr for NOSIX.

Performance

PRBLX vs. NOSIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Parnassus Core Equity Fund Investor Shares (PRBLX) and Northern Stock Index Fund (NOSIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, PRBLX achieves a 7.76% return, which is significantly lower than NOSIX's 9.34% return. Over the past 10 years, PRBLX has underperformed NOSIX with an annualized return of 13.50%, while NOSIX has yielded a comparatively higher 14.90% annualized return.

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%

NOSIX

• 1D: 1.65%
• 1M: -0.56%
• 6M: 7.78%
• YTD: 9.34%
• 1Y: 18.69%
• 3Y*: 18.98%
• 5Y*: 12.60%
• 10Y*: 14.90%
• ALL TIME*: 9.90%

*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)
NOSIX Northern Stock Index Fund	$0.00	$0.00	$0.00
PRBLX Parnassus Core Equity Fund Investor Shares	$0.00	$0.00	$0.00

PRBLX vs. NOSIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
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%
NOSIX Northern Stock Index Fund	9.34%	17.83%	24.87%	26.24%	-18.25%	28.55%	18.33%	31.35%	-4.54%	21.71%

Correlation

The correlation between PRBLX and NOSIX is 0.80, 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.	0.80
Correlation (3Y) Balances recent behavior with more history.	0.88
Correlation (5Y) Shows whether the relationship held over a longer period.	0.92
Correlation (10Y) Provides a long-term view across more market conditions.	0.93
Correlation (All Time) Calculated using the full available price history since Oct 7, 1996	0.89

The correlation between PRBLX and NOSIX shifts across timeframes, from 0.80 (1 year) to 0.93 (10 years), reflecting how their relationship changes across market environments.

Return for Risk

PRBLX vs. NOSIX — Risk / Return Rank

Compare historical risk-adjusted metric ranks over the past 12 months.

PRBLX

PRBLX Risk / Return Rank: 20
PRBLX Sharpe Ratio Rank: 20
PRBLX Sortino Ratio Rank: 20
PRBLX Omega Ratio Rank: 19
PRBLX Calmar Ratio Rank: 17
PRBLX Martin Ratio Rank: 23

NOSIX

NOSIX Risk / Return Rank: 62
NOSIX Sharpe Ratio Rank: 58
NOSIX Sortino Ratio Rank: 56
NOSIX Omega Ratio Rank: 57
NOSIX Calmar Ratio Rank: 63
NOSIX Martin Ratio Rank: 74

The rank (0–100) uses a weighted average of the Sharpe, Sortino, Omega, Calmar, and Martin percentile ranks for the trailing 12 months. Higher means stronger historical risk-adjusted performance within the peer group.

PRBLX vs. NOSIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Parnassus Core Equity Fund Investor Shares (PRBLX) and Northern Stock Index Fund (NOSIX). 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.

	PRBLX	NOSIX	Difference
Sharpe ratio: Return per unit of total volatility	0.71	1.41	-0.70
Sortino ratio: Return per unit of downside risk	1.07	2.00	-0.92
Omega ratio: Gain probability vs. loss probability	1.13	1.26	-0.13
Calmar ratio: Return relative to maximum drawdown	0.79	2.05	-1.26
Martin ratio: Return relative to average drawdown	3.05	8.82	-5.77

PRBLX vs. NOSIX - Sharpe Ratio Comparison

The current PRBLX Sharpe Ratio is 0.71, which is lower than the NOSIX Sharpe Ratio of 1.41. The chart below compares the historical Sharpe Ratios of PRBLX and NOSIX, 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

PRBLX vs. NOSIX - Drawdown Comparison

The maximum PRBLX drawdown since its inception was -42.20%, smaller than the maximum NOSIX drawdown of -55.42%. Use the drawdown chart below to compare losses from any high point for PRBLX and NOSIX.

Drawdown Indicators

	PRBLX	NOSIX	Difference
Max Drawdown Largest peak-to-trough decline	-42.20%	-55.42%	+13.22%
Max Drawdown (1Y) Largest decline over 1 year	-11.63%	-8.89%	-2.74%
Max Drawdown (3Y) Largest decline over 3 years	-16.31%	-18.75%	+2.44%
Max Drawdown (5Y) Largest decline over 5 years	-26.31%	-24.54%	-1.77%
Max Drawdown (10Y) Largest decline over 10 years	-30.09%	-33.82%	+3.73%
Current Drawdown Current decline from peak	-1.70%	-2.09%	+0.39%
Average Drawdown Average peak-to-trough decline	-4.03%	-10.28%	+6.25%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.03%	2.06%	+0.97%

Volatility

PRBLX vs. NOSIX - Volatility Comparison

Parnassus Core Equity Fund Investor Shares (PRBLX) has a higher volatility of 3.70% compared to Northern Stock Index Fund (NOSIX) at 3.43%. This indicates that PRBLX's price experiences larger fluctuations and is considered to be riskier than NOSIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	PRBLX	NOSIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.70%	3.43%	+0.27%
Volatility (6M) Calculated over the trailing 6-month period	10.38%	10.06%	+0.32%
Volatility (1Y) Calculated over the trailing 1-year period	12.90%	12.90%	0.00%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.40%	17.31%	-0.91%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	17.28%	18.21%	-0.93%

PRBLX vs. NOSIX - Expense Ratio Comparison

PRBLX has a 0.81% expense ratio, which is higher than NOSIX's 0.05% expense ratio.

Dividends

PRBLX vs. NOSIX - Dividend Comparison

PRBLX's dividend yield for the trailing twelve months is around 17.66%, more than NOSIX's 2.73% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
NOSIX Northern Stock Index Fund	2.73%	2.94%	2.59%	5.02%	4.72%	3.22%	4.00%	2.41%	4.82%	3.13%	2.76%	3.36%
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%

Frequently Asked Questions

Can I hold both PRBLX and NOSIX in my portfolio?

PRBLX and NOSIX 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, PRBLX or NOSIX?

PRBLX has higher volatility (3.70%) compared to NOSIX (3.43%). In terms of maximum drawdown, PRBLX dropped -42.20% vs NOSIX's -55.42%.

Which has better risk-adjusted returns?

NOSIX currently has the higher Sharpe Ratio (1.41 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.