VIIIX vs. VEMPX

Last updated Jun 23, 2026

VIIIX (Vanguard Institutional Index Fund Institutional Plus Shares) and VEMPX (Vanguard Extended Market Index Fund Institutional Plus Shares) are both mutual funds - VIIIX is a S&P 500 fund tracking the S&P 500 Index, while VEMPX is a Mid Cap Blend Equities fund managed by Vanguard. Over the past 10 years, VIIIX returned 15.65%/yr vs 12.35%/yr for VEMPX. Their correlation of 0.88 suggests significant overlap in exposure. VIIIX charges 0.02%/yr vs 0.04%/yr for VEMPX.

Performance

VIIIX vs. VEMPX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) and Vanguard Extended Market Index Fund Institutional Plus Shares (VEMPX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, VIIIX achieves a 10.19% return, which is significantly lower than VEMPX's 15.71% return. Over the past 10 years, VIIIX has outperformed VEMPX with an annualized return of 15.65%, while VEMPX has yielded a comparatively lower 12.35% annualized return.

VIIIX

• 1D: 1.09%
• 1M: 0.47%
• YTD: 10.19%
• 6M: 9.68%
• 1Y: 27.18%
• 3Y*: 21.39%
• 5Y*: 14.24%
• 10Y*: 15.65%

VEMPX

• 1D: 1.66%
• 1M: 4.42%
• YTD: 15.71%
• 6M: 12.70%
• 1Y: 30.65%
• 3Y*: 19.15%
• 5Y*: 6.97%
• 10Y*: 12.35%

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

VIIIX vs. VEMPX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares	10.19%	17.87%	26.29%	25.79%	-18.14%	28.69%	18.41%	31.48%	-4.41%	21.82%
VEMPX Vanguard Extended Market Index Fund Institutional Plus Shares	15.71%	11.43%	15.50%	26.98%	-26.45%	12.48%	32.24%	28.06%	-9.35%	18.13%

Correlation

The correlation between VIIIX and VEMPX is 0.84, 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	0.84
Correlation (3Y) Calculated over the trailing 3-year period	0.83
Correlation (5Y) Calculated over the trailing 5-year period	0.86
Correlation (10Y) Calculated over the trailing 10-year period	0.86
Correlation (All Time) Calculated using the full available price history since Dec 13, 2010	0.88

The correlation between VIIIX and VEMPX has been stable across timeframes, ranging from 0.83 to 0.88 - a consistent structural relationship.

VIIIX vs. VEMPX - Sectors Allocation Comparison

Sectors	VIIIX	VEMPX
Technology	39.1%	22.8%
Financial Services	10.9%	14.0%
Communication Services	10.7%	3.2%
Consumer Cyclical	9.9%	9.2%
Healthcare	8.3%	12.9%
Industrials	7.8%	19.3%
Consumer Defensive	4.5%	2.5%
Energy	3.1%	4.4%
Utilities	2.1%	1.9%
Real Estate	1.8%	5.8%
Basic Materials	1.7%	4.2%

Return for Risk

VIIIX vs. VEMPX — Risk / Return Rank

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

VIIIX

VIIIX Risk / Return Rank: 66
VIIIX Sharpe Ratio Rank: 64
VIIIX Sortino Ratio Rank: 59
VIIIX Omega Ratio Rank: 61
VIIIX Calmar Ratio Rank: 68
VIIIX Martin Ratio Rank: 79

VEMPX

VEMPX Risk / Return Rank: 47
VEMPX Sharpe Ratio Rank: 40
VEMPX Sortino Ratio Rank: 38
VEMPX Omega Ratio Rank: 36
VEMPX Calmar Ratio Rank: 66
VEMPX Martin Ratio Rank: 55

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.

VIIIX vs. VEMPX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) and Vanguard Extended Market Index Fund Institutional Plus Shares (VEMPX). 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.

	VIIIX	VEMPX	Difference
Sharpe ratio: Return per unit of total volatility	2.17	1.72	+0.45
Sortino ratio: Return per unit of downside risk	2.93	2.40	+0.53
Omega ratio: Gain probability vs. loss probability	1.39	1.29	+0.10
Calmar ratio: Return relative to maximum drawdown	3.04	2.98	+0.06
Martin ratio: Return relative to average drawdown	13.74	10.46	+3.28

VIIIX vs. VEMPX - Sharpe Ratio Comparison

The current VIIIX Sharpe Ratio is 2.17, which is comparable to the VEMPX Sharpe Ratio of 1.72. The chart below compares the historical Sharpe Ratios of VIIIX and VEMPX, 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

VIIIX vs. VEMPX - Drawdown Comparison

The maximum VIIIX drawdown since its inception was -55.18%, which is greater than VEMPX's maximum drawdown of -41.62%. Use the drawdown chart below to compare losses from any high point for VIIIX and VEMPX.

Drawdown Indicators

	VIIIX	VEMPX	Difference
Max Drawdown Largest peak-to-trough decline	-55.18%	-41.62%	-13.56%
Max Drawdown (1Y) Largest decline over 1 year	-8.90%	-10.25%	+1.35%
Max Drawdown (3Y) Largest decline over 3 years	-18.75%	-26.83%	+8.08%
Max Drawdown (5Y) Largest decline over 5 years	-24.50%	-36.32%	+11.82%
Max Drawdown (10Y) Largest decline over 10 years	-33.79%	-41.62%	+7.83%
Current Drawdown Current decline from peak	-1.36%	-0.12%	-1.24%
Average Drawdown Average peak-to-trough decline	-10.00%	-7.95%	-2.05%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.96%	2.91%	-0.95%

Volatility

VIIIX vs. VEMPX - Volatility Comparison

The current volatility for Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) is 4.77%, while Vanguard Extended Market Index Fund Institutional Plus Shares (VEMPX) has a volatility of 6.37%. This indicates that VIIIX experiences smaller price fluctuations and is considered to be less risky than VEMPX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	VIIIX	VEMPX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.77%	6.37%	-1.60%
Volatility (6M) Calculated over the trailing 6-month period	9.91%	13.33%	-3.42%
Volatility (1Y) Calculated over the trailing 1-year period	12.47%	17.81%	-5.34%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.99%	22.45%	-5.46%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	18.10%	22.41%	-4.31%

VIIIX vs. VEMPX - Expense Ratio Comparison

VIIIX has a 0.02% expense ratio, which is lower than VEMPX's 0.04% expense ratio. Despite the difference, both funds are considered low-cost compared to the broader market, where average expense ratios usually range from 0.3% to 0.9%.

Dividends

VIIIX vs. VEMPX - Dividend Comparison

VIIIX's dividend yield for the trailing twelve months is around 2.44%, more than VEMPX's 1.01% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
VEMPX Vanguard Extended Market Index Fund Institutional Plus Shares	1.01%	1.15%	1.11%	1.27%	1.17%	1.15%	1.09%	1.32%	1.68%	1.27%	1.46%	1.39%
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares	2.44%	2.11%	3.66%	2.66%	3.39%	4.79%	3.07%	2.86%	2.45%	1.84%	2.38%	2.47%

Frequently Asked Questions

Can I hold both VIIIX and VEMPX in my portfolio?

VIIIX and VEMPX have a correlation of 0.84, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, VIIIX or VEMPX?

VEMPX has higher volatility (6.37%) compared to VIIIX (4.77%). In terms of maximum drawdown, VIIIX dropped -55.18% vs VEMPX's -41.62%.

Which has better risk-adjusted returns?

VIIIX currently has the higher Sharpe Ratio (2.17 vs 1.72), 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.