VPMAX vs. POSKX

Last updated Jun 4, 2026

VPMAX (Vanguard PRIMECAP Fund Admiral Shares) and POSKX (PrimeCap Odyssey Stock Fund) are both Large Cap Blend Equities funds. Over the past 10 years, VPMAX returned 17.65%/yr vs 16.24%/yr for POSKX. With a 0.97 correlation, they move nearly in lockstep. VPMAX charges 0.31%/yr vs 0.65%/yr for POSKX.

Performance

VPMAX vs. POSKX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard PRIMECAP Fund Admiral Shares (VPMAX) and PrimeCap Odyssey Stock Fund (POSKX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, VPMAX achieves a 25.44% return, which is significantly higher than POSKX's 22.10% return. Over the past 10 years, VPMAX has outperformed POSKX with an annualized return of 17.65%, while POSKX has yielded a comparatively lower 16.24% annualized return.

VPMAX

• 1D: 0.35%
• 1M: 12.86%
• YTD: 25.44%
• 6M: 26.85%
• 1Y: 58.91%
• 3Y*: 28.09%
• 5Y*: 16.52%
• 10Y*: 17.65%

POSKX

• 1D: 0.52%
• 1M: 9.11%
• YTD: 22.10%
• 6M: 22.48%
• 1Y: 50.17%
• 3Y*: 25.06%
• 5Y*: 15.87%
• 10Y*: 16.24%

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

VPMAX vs. POSKX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VPMAX Vanguard PRIMECAP Fund Admiral Shares	25.44%	29.70%	13.30%	28.25%	-15.16%	21.72%	17.23%	27.88%	-1.93%	28.28%
POSKX PrimeCap Odyssey Stock Fund	22.10%	25.73%	12.77%	21.18%	-11.12%	32.48%	10.13%	27.15%	-7.19%	25.99%

Correlation

The correlation between VPMAX and POSKX is 0.93, 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	0.93
Correlation (3Y) Calculated over the trailing 3-year period	0.94
Correlation (5Y) Calculated over the trailing 5-year period	0.96
Correlation (10Y) Calculated over the trailing 10-year period	0.96
Correlation (All Time) Calculated using the full available price history since Nov 3, 2004	0.97

The correlation between VPMAX and POSKX has been stable across timeframes, ranging from 0.93 to 0.97 - a consistent structural relationship.

Return for Risk

VPMAX vs. POSKX — Risk / Return Rank

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

VPMAX

VPMAX Risk / Return Rank: 94
VPMAX Sharpe Ratio Rank: 97
VPMAX Sortino Ratio Rank: 95
VPMAX Omega Ratio Rank: 91
VPMAX Calmar Ratio Rank: 93
VPMAX Martin Ratio Rank: 96

POSKX

POSKX Risk / Return Rank: 91
POSKX Sharpe Ratio Rank: 94
POSKX Sortino Ratio Rank: 91
POSKX Omega Ratio Rank: 85
POSKX Calmar Ratio Rank: 93
POSKX Martin Ratio Rank: 94

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.

VPMAX vs. POSKX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard PRIMECAP Fund Admiral Shares (VPMAX) and PrimeCap Odyssey Stock Fund (POSKX). 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.

	VPMAX	POSKX	Difference
Sharpe ratio: Return per unit of total volatility	3.76	3.25	+0.51
Sortino ratio: Return per unit of downside risk	5.05	4.48	+0.58
Omega ratio: Gain probability vs. loss probability	1.66	1.57	+0.08
Calmar ratio: Return relative to maximum drawdown	5.14	5.18	-0.04
Martin ratio: Return relative to average drawdown	23.68	21.69	+2.00
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VPMAX vs. POSKX - Sharpe Ratio Comparison

The current VPMAX Sharpe Ratio is 3.76, which is comparable to the POSKX Sharpe Ratio of 3.25. The chart below compares the historical Sharpe Ratios of VPMAX and POSKX, 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

	VPMAX	POSKX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	3.76	3.25	+0.51
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.91	0.89	+0.02
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.92	0.86	+0.07
Sharpe Ratio (All Time) Calculated using the full available price history	0.65	0.67	-0.02

Drawdowns

VPMAX vs. POSKX - Drawdown Comparison

The maximum VPMAX drawdown since its inception was -48.32%, roughly equal to the maximum POSKX drawdown of -50.18%. Use the drawdown chart below to compare losses from any high point for VPMAX and POSKX.

Drawdown Indicators

	VPMAX	POSKX	Difference
Max Drawdown Largest peak-to-trough decline	-48.32%	-50.18%	+1.86%
Max Drawdown (1Y) Largest decline over 1 year	-11.72%	-9.99%	-1.73%
Max Drawdown (3Y) Largest decline over 3 years	-20.55%	-20.25%	-0.30%
Max Drawdown (5Y) Largest decline over 5 years	-25.21%	-22.96%	-2.25%
Max Drawdown (10Y) Largest decline over 10 years	-32.65%	-36.88%	+4.23%
Current Drawdown Current decline from peak	0.00%	-0.12%	+0.12%
Average Drawdown Average peak-to-trough decline	-6.58%	-6.15%	-0.43%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.54%	2.38%	+0.16%

Volatility

VPMAX vs. POSKX - Volatility Comparison

Vanguard PRIMECAP Fund Admiral Shares (VPMAX) and PrimeCap Odyssey Stock Fund (POSKX) have volatilities of 6.18% and 6.13%, respectively, indicating that both stocks experience similar levels of price fluctuations. This suggests that the risk associated with both stocks, as measured by volatility, is nearly the same. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VPMAX	POSKX	Difference
Volatility (1M) Calculated over the trailing 1-month period	6.18%	6.13%	+0.05%
Volatility (6M) Calculated over the trailing 6-month period	12.85%	12.66%	+0.19%
Volatility (1Y) Calculated over the trailing 1-year period	16.02%	15.92%	+0.10%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	18.26%	17.87%	+0.39%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	19.19%	19.00%	+0.19%

VPMAX vs. POSKX - Expense Ratio Comparison

VPMAX has a 0.31% expense ratio, which is lower than POSKX's 0.65% expense ratio.

Dividends

VPMAX vs. POSKX - Dividend Comparison

VPMAX's dividend yield for the trailing twelve months is around 13.12%, less than POSKX's 22.47% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
POSKX PrimeCap Odyssey Stock Fund	22.47%	27.44%	18.13%	10.14%	12.13%	14.58%	7.85%	6.03%	3.03%	2.17%	2.93%	1.92%
VPMAX Vanguard PRIMECAP Fund Admiral Shares	13.12%	16.46%	6.71%	7.24%	9.94%	10.18%	9.82%	7.23%	8.43%	4.52%	5.13%	5.99%

Frequently Asked Questions

Can I hold both VPMAX and POSKX in my portfolio?

With a correlation of 0.93, VPMAX and POSKX 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, VPMAX or POSKX?

VPMAX has higher volatility (6.18%) compared to POSKX (6.13%). In terms of maximum drawdown, VPMAX dropped -48.32% vs POSKX's -50.18%.

Which has better risk-adjusted returns?

VPMAX currently has the higher Sharpe Ratio (3.76 vs 3.25), 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.