VIIIX vs. FXAIX

Last updated Jun 4, 2026

VIIIX (Vanguard Institutional Index Fund Institutional Plus Shares) and FXAIX (Fidelity 500 Index Fund) are both S&P 500 funds tracking the S&P 500 Index, from Vanguard and Fidelity respectively. Both are passively managed. Over the past 10 years, VIIIX returned 15.74%/yr vs 15.66%/yr for FXAIX. With a 1.00 correlation, they move nearly in lockstep. Both charge a 0.02% expense ratio.

Performance

VIIIX vs. FXAIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) and Fidelity 500 Index Fund (FXAIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

The year-to-date returns for both investments are quite close, with VIIIX having a 11.70% return and FXAIX slightly higher at 11.71%. Both investments have delivered pretty close results over the past 10 years, with VIIIX having a 15.74% annualized return and FXAIX not far behind at 15.66%.

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%

FXAIX

• 1D: 0.13%
• 1M: 5.80%
• YTD: 11.71%
• 6M: 11.74%
• 1Y: 28.99%
• 3Y*: 22.75%
• 5Y*: 14.28%
• 10Y*: 15.66%

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

VIIIX vs. FXAIX - 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%
FXAIX Fidelity 500 Index Fund	11.71%	17.84%	25.01%	26.29%	-18.14%	28.71%	18.42%	31.48%	-4.43%	21.82%

Correlation

The correlation between VIIIX and FXAIX is 1.00 - these two move nearly in lockstep. At this level, holding both provides almost no diversification benefit. If you already own one, adding the other does little to reduce portfolio risk.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	1.00
Correlation (3Y) Calculated over the trailing 3-year period	1.00
Correlation (5Y) Calculated over the trailing 5-year period	1.00
Correlation (10Y) Calculated over the trailing 10-year period	1.00
Correlation (All Time) Calculated using the full available price history since May 5, 2011	1.00

The correlation between VIIIX and FXAIX has been stable across timeframes, ranging from 1.00 to 1.00 - a consistent structural relationship.

Return for Risk

VIIIX vs. FXAIX — 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

FXAIX

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

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. FXAIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) and Fidelity 500 Index Fund (FXAIX). 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	FXAIX	Difference
Sharpe ratio: Return per unit of total volatility	2.52	2.52	0.00
Sortino ratio: Return per unit of downside risk	3.42	3.42	0.00
Omega ratio: Gain probability vs. loss probability	1.46	1.46	0.00
Calmar ratio: Return relative to maximum drawdown	3.36	3.36	0.00
Martin ratio: Return relative to average drawdown	15.69	15.70	0.00
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

VIIIX vs. FXAIX - Sharpe Ratio Comparison

The current VIIIX Sharpe Ratio is 2.52, which is comparable to the FXAIX Sharpe Ratio of 2.52. The chart below compares the historical Sharpe Ratios of VIIIX and FXAIX, 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	FXAIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.52	2.52	0.00
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.86	0.85	+0.01
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.87	0.87	0.00
Sharpe Ratio (All Time) Calculated using the full available price history	0.50	0.82	-0.33

Drawdowns

VIIIX vs. FXAIX - Drawdown Comparison

The maximum VIIIX drawdown since its inception was -55.18%, which is greater than FXAIX's maximum drawdown of -33.79%. Use the drawdown chart below to compare losses from any high point for VIIIX and FXAIX.

Drawdown Indicators

	VIIIX	FXAIX	Difference
Max Drawdown Largest peak-to-trough decline	-55.18%	-33.79%	-21.39%
Max Drawdown (1Y) Largest decline over 1 year	-8.90%	-8.89%	-0.01%
Max Drawdown (3Y) Largest decline over 3 years	-18.75%	-18.76%	+0.01%
Max Drawdown (5Y) Largest decline over 5 years	-24.50%	-24.50%	0.00%
Max Drawdown (10Y) Largest decline over 10 years	-33.79%	-33.79%	0.00%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-10.02%	-3.79%	-6.23%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.90%	1.90%	0.00%

Volatility

VIIIX vs. FXAIX - Volatility Comparison

Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) and Fidelity 500 Index Fund (FXAIX) have volatilities of 2.83% and 2.83%, 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	FXAIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	2.83%	2.83%	0.00%
Volatility (6M) Calculated over the trailing 6-month period	8.97%	8.97%	0.00%
Volatility (1Y) Calculated over the trailing 1-year period	11.86%	11.86%	0.00%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.89%	16.91%	-0.02%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	18.06%	18.07%	-0.01%

VIIIX vs. FXAIX - Expense Ratio Comparison

Both VIIIX and FXAIX have an expense ratio of 0.02%, making them cost-effective options compared to the broader market, where average expense ratios typically range from 0.3% to 0.9%.

Dividends

VIIIX vs. FXAIX - Dividend Comparison

VIIIX's dividend yield for the trailing twelve months is around 2.41%, more than FXAIX's 1.03% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FXAIX Fidelity 500 Index Fund	1.03%	1.11%	1.25%	1.45%	1.69%	1.22%	1.60%	2.06%	2.72%	1.97%	2.52%	2.83%
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%

Frequently Asked Questions

Can I hold both VIIIX and FXAIX in my portfolio?

With a correlation of 1.00, VIIIX and FXAIX 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, VIIIX or FXAIX?

FXAIX has higher volatility (2.83%) compared to VIIIX (2.83%). In terms of maximum drawdown, VIIIX dropped -55.18% vs FXAIX's -33.79%.

Which has better risk-adjusted returns?

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