SSSYX vs. VIIIX

Last updated Jun 4, 2026

SSSYX (State Street Equity 500 Index Fund Class K) and VIIIX (Vanguard Institutional Index Fund Institutional Plus Shares) are both Large Cap Blend Equities funds. Over the past 10 years, SSSYX returned 15.61%/yr vs 15.74%/yr for VIIIX. With a 0.99 correlation, they move nearly in lockstep. Both charge a 0.02% expense ratio.

Performance

SSSYX vs. VIIIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in State Street Equity 500 Index Fund Class K (SSSYX) and Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX). 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 SSSYX having a 11.69% return and VIIIX slightly higher at 11.70%. Both investments have delivered pretty close results over the past 10 years, with SSSYX having a 15.61% annualized return and VIIIX not far ahead at 15.74%.

SSSYX

• 1D: 0.14%
• 1M: 5.79%
• YTD: 11.69%
• 6M: 11.73%
• 1Y: 28.94%
• 3Y*: 22.73%
• 5Y*: 14.24%
• 10Y*: 15.61%

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%

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

SSSYX vs. VIIIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
SSSYX State Street Equity 500 Index Fund Class K	11.69%	17.81%	24.99%	26.27%	-18.16%	28.51%	18.31%	31.38%	-4.38%	21.61%
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%

Correlation

The correlation between SSSYX and VIIIX 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	0.99
Correlation (All Time) Calculated using the full available price history since Sep 19, 2014	0.99

The correlation between SSSYX and VIIIX has been stable across timeframes, ranging from 0.99 to 1.00 - a consistent structural relationship.

Return for Risk

SSSYX vs. VIIIX — Risk / Return Rank

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

SSSYX

SSSYX Risk / Return Rank: 73
SSSYX Sharpe Ratio Rank: 75
SSSYX Sortino Ratio Rank: 67
SSSYX Omega Ratio Rank: 67
SSSYX Calmar Ratio Rank: 74
SSSYX Martin Ratio Rank: 83

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

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.

SSSYX vs. VIIIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for State Street Equity 500 Index Fund Class K (SSSYX) and Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX). 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.

	SSSYX	VIIIX	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	15.69	-0.01
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

SSSYX vs. VIIIX - Sharpe Ratio Comparison

The current SSSYX Sharpe Ratio is 2.52, which is comparable to the VIIIX Sharpe Ratio of 2.52. The chart below compares the historical Sharpe Ratios of SSSYX and VIIIX, 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

	SSSYX	VIIIX	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	0.85	0.86	-0.01
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.13	0.87	-0.75
Sharpe Ratio (All Time) Calculated using the full available price history	0.12	0.50	-0.38

Drawdowns

SSSYX vs. VIIIX - Drawdown Comparison

The maximum SSSYX drawdown since its inception was -91.48%, which is greater than VIIIX's maximum drawdown of -55.18%. Use the drawdown chart below to compare losses from any high point for SSSYX and VIIIX.

Drawdown Indicators

	SSSYX	VIIIX	Difference
Max Drawdown Largest peak-to-trough decline	-91.48%	-55.18%	-36.30%
Max Drawdown (1Y) Largest decline over 1 year	-8.88%	-8.90%	+0.02%
Max Drawdown (3Y) Largest decline over 3 years	-18.74%	-18.75%	+0.01%
Max Drawdown (5Y) Largest decline over 5 years	-24.49%	-24.50%	+0.01%
Max Drawdown (10Y) Largest decline over 10 years	-91.48%	-33.79%	-57.69%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-4.15%	-10.02%	+5.87%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.90%	1.90%	0.00%

Volatility

SSSYX vs. VIIIX - Volatility Comparison

State Street Equity 500 Index Fund Class K (SSSYX) and Vanguard Institutional Index Fund Institutional Plus Shares (VIIIX) have volatilities of 2.82% 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

	SSSYX	VIIIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	2.82%	2.83%	-0.01%
Volatility (6M) Calculated over the trailing 6-month period	8.96%	8.97%	-0.01%
Volatility (1Y) Calculated over the trailing 1-year period	11.85%	11.86%	-0.01%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.88%	16.89%	-0.01%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	124.46%	18.06%	+106.40%

SSSYX vs. VIIIX - Expense Ratio Comparison

Both SSSYX and VIIIX 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

SSSYX vs. VIIIX - Dividend Comparison

SSSYX's dividend yield for the trailing twelve months is around 1.29%, less than VIIIX's 2.41% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
SSSYX State Street Equity 500 Index Fund Class K	1.29%	1.44%	1.63%	1.78%	2.16%	2.76%	1.86%	4.44%	5.18%	5.94%	2.07%	1.84%
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 SSSYX and VIIIX in my portfolio?

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

VIIIX has higher volatility (2.83%) compared to SSSYX (2.82%). In terms of maximum drawdown, SSSYX dropped -91.48% vs VIIIX's -55.18%.

Which has better risk-adjusted returns?

VIIIX 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.