VIIIX vs. VMCIX

Last updated Jun 4, 2026

VIIIX (Vanguard Institutional Index Fund Institutional Plus Shares) and VMCIX (Vanguard Mid-Cap Index Fund Institutional Shares) are both mutual funds - VIIIX is a S&P 500 fund tracking the S&P 500 Index, while VMCIX is a Mid Cap Blend Equities fund managed by Vanguard. Over the past 10 years, VIIIX returned 15.74%/yr vs 11.59%/yr for VMCIX. Their correlation of 0.91 suggests significant overlap in exposure. VIIIX charges 0.02%/yr vs 0.04%/yr for VMCIX.

Performance

VIIIX vs. VMCIX - 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 Mid-Cap Index Fund Institutional Shares (VMCIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, VIIIX achieves a 11.70% return, which is significantly higher than VMCIX's 10.56% return. Over the past 10 years, VIIIX has outperformed VMCIX with an annualized return of 15.74%, while VMCIX has yielded a comparatively lower 11.59% annualized return.

VIIIX

• 1D: 0.13%
• 1M: 5.80%
• YTD: 11.70%
• 6M: 11.74%
• 1Y: 28.99%
• 3Y*: 23.17%
• 5Y*: 14.42%
• 10Y*: 15.74%

VMCIX

• 1D: 0.90%
• 1M: 3.69%
• YTD: 10.56%
• 6M: 10.21%
• 1Y: 18.75%
• 3Y*: 16.83%
• 5Y*: 8.11%
• 10Y*: 11.59%

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

VIIIX vs. VMCIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares	11.70%	17.87%	26.29%	25.79%	-18.14%	28.69%	18.41%	31.48%	-4.41%	21.82%
VMCIX Vanguard Mid-Cap Index Fund Institutional Shares	10.56%	11.67%	14.68%	16.54%	-18.70%	24.53%	18.20%	31.04%	-9.25%	19.30%

Correlation

The correlation between VIIIX and VMCIX is 0.78, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.78
Correlation (3Y) Calculated over the trailing 3-year period	0.83
Correlation (5Y) Calculated over the trailing 5-year period	0.89
Correlation (10Y) Calculated over the trailing 10-year period	0.91
Correlation (All Time) Calculated using the full available price history since May 22, 1998	0.91

The correlation between VIIIX and VMCIX shifts across timeframes, from 0.78 (1 year) to 0.91 (all time), reflecting how their relationship changes across market environments.

VIIIX vs. VMCIX - Sectors Allocation Comparison

Sectors	VIIIX	VMCIX
Technology	35.5%	18.6%
Financial Services	11.6%	12.8%
Communication Services	11.1%	3.1%
Consumer Cyclical	10.0%	8.6%
Healthcare	8.5%	7.6%
Industrials	8.0%	17.9%
Consumer Defensive	4.9%	4.8%
Energy	3.5%	8.5%
Utilities	2.8%	8.3%
Real Estate	1.9%	5.4%
Basic Materials	1.8%	4.2%

Return for Risk

VIIIX vs. VMCIX — Risk / Return Rank

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

VIIIX

VIIIX Risk / Return Rank: 73
VIIIX Sharpe Ratio Rank: 76
VIIIX Sortino Ratio Rank: 67
VIIIX Omega Ratio Rank: 67
VIIIX Calmar Ratio Rank: 74
VIIIX Martin Ratio Rank: 83

VMCIX

VMCIX Risk / Return Rank: 35
VMCIX Sharpe Ratio Rank: 32
VMCIX Sortino Ratio Rank: 31
VMCIX Omega Ratio Rank: 29
VMCIX Calmar Ratio Rank: 42
VMCIX Martin Ratio Rank: 44

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. VMCIX - 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 Mid-Cap Index Fund Institutional Shares (VMCIX). 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.

	VIIIX	VMCIX	Difference
Sharpe ratio: Return per unit of total volatility	2.52	1.62	+0.90
Sortino ratio: Return per unit of downside risk	3.42	2.31	+1.12
Omega ratio: Gain probability vs. loss probability	1.46	1.28	+0.18
Calmar ratio: Return relative to maximum drawdown	3.36	2.45	+0.91
Martin ratio: Return relative to average drawdown	15.69	9.29	+6.40
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VIIIX vs. VMCIX - Sharpe Ratio Comparison

The current VIIIX Sharpe Ratio is 2.52, which is higher than the VMCIX Sharpe Ratio of 1.62. The chart below compares the historical Sharpe Ratios of VIIIX and VMCIX, 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

	VIIIX	VMCIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.52	1.62	+0.90
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.86	0.46	+0.40
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.87	0.61	+0.26
Sharpe Ratio (All Time) Calculated using the full available price history	0.50	0.49	+0.01

Drawdowns

VIIIX vs. VMCIX - Drawdown Comparison

The maximum VIIIX drawdown since its inception was -55.18%, smaller than the maximum VMCIX drawdown of -58.86%. Use the drawdown chart below to compare losses from any high point for VIIIX and VMCIX.

Drawdown Indicators

	VIIIX	VMCIX	Difference
Max Drawdown Largest peak-to-trough decline	-55.18%	-58.86%	+3.68%
Max Drawdown (1Y) Largest decline over 1 year	-8.90%	-8.13%	-0.77%
Max Drawdown (3Y) Largest decline over 3 years	-18.75%	-18.93%	+0.18%
Max Drawdown (5Y) Largest decline over 5 years	-24.50%	-27.54%	+3.04%
Max Drawdown (10Y) Largest decline over 10 years	-33.79%	-39.30%	+5.51%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-10.02%	-7.97%	-2.05%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.90%	2.14%	-0.24%

Volatility

VIIIX vs. VMCIX - Volatility Comparison

Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) and Vanguard Mid-Cap Index Fund Institutional Shares (VMCIX) have volatilities of 2.83% and 2.97%, 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

	VIIIX	VMCIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	2.83%	2.97%	-0.14%
Volatility (6M) Calculated over the trailing 6-month period	8.97%	9.29%	-0.32%
Volatility (1Y) Calculated over the trailing 1-year period	11.86%	12.31%	-0.45%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.89%	17.63%	-0.74%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	18.06%	18.92%	-0.86%

VIIIX vs. VMCIX - Expense Ratio Comparison

VIIIX has a 0.02% expense ratio, which is lower than VMCIX'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. VMCIX - Dividend Comparison

VIIIX's dividend yield for the trailing twelve months is around 2.41%, more than VMCIX's 1.35% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
VIIIX Vanguard Institutional Index Fund Institutional Plus Shares	2.41%	2.11%	3.66%	2.66%	3.39%	4.79%	3.07%	2.86%	2.45%	1.84%	2.38%	2.47%
VMCIX Vanguard Mid-Cap Index Fund Institutional Shares	1.35%	1.52%	1.49%	1.51%	1.60%	1.12%	1.45%	1.48%	1.83%	1.36%	1.46%	1.48%

Frequently Asked Questions

Can I hold both VIIIX and VMCIX in my portfolio?

VIIIX and VMCIX have a correlation of 0.78, 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 VMCIX?

VMCIX has higher volatility (2.97%) compared to VIIIX (2.83%). In terms of maximum drawdown, VIIIX dropped -55.18% vs VMCIX's -58.86%.

Which has better risk-adjusted returns?

VIIIX currently has the higher Sharpe Ratio (2.52 vs 1.62), 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.