SSSYX vs. SSMKX

Last updated Jun 4, 2026

SSSYX (State Street Equity 500 Index Fund Class K) and SSMKX (State Street Small/Mid Cap Equity Index Fund) are both mutual funds - SSSYX is a Large Cap Blend Equities fund tracking the S&P 500 Index, while SSMKX is a Mid Cap Blend Equities fund managed by State Street. Over the past 10 years, SSSYX returned 15.61%/yr vs 12.48%/yr for SSMKX. Their correlation of 0.86 suggests significant overlap in exposure. SSSYX charges 0.02%/yr vs 0.04%/yr for SSMKX.

Performance

SSSYX vs. SSMKX - 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 State Street Small/Mid Cap Equity Index Fund (SSMKX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, SSSYX achieves a 11.69% return, which is significantly lower than SSMKX's 14.17% return. Over the past 10 years, SSSYX has outperformed SSMKX with an annualized return of 15.61%, while SSMKX has yielded a comparatively lower 12.48% annualized return.

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%

SSMKX

• 1D: 1.00%
• 1M: 5.71%
• YTD: 14.17%
• 6M: 13.00%
• 1Y: 29.82%
• 3Y*: 20.36%
• 5Y*: 7.43%
• 10Y*: 12.48%

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

SSSYX vs. SSMKX - 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%
SSMKX State Street Small/Mid Cap Equity Index Fund	14.17%	12.77%	17.20%	25.20%	-25.49%	12.38%	32.41%	27.82%	-9.02%	18.16%

Correlation

The correlation between SSSYX and SSMKX is 0.83, 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	0.83
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	0.85
Correlation (All Time) Calculated using the full available price history since Jan 5, 2016	0.86

The correlation between SSSYX and SSMKX has been stable across timeframes, ranging from 0.83 to 0.86 - a consistent structural relationship.

Return for Risk

SSSYX vs. SSMKX — 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

SSMKX

SSMKX Risk / Return Rank: 48
SSMKX Sharpe Ratio Rank: 42
SSMKX Sortino Ratio Rank: 40
SSMKX Omega Ratio Rank: 37
SSMKX Calmar Ratio Rank: 67
SSMKX Martin Ratio Rank: 57

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. SSMKX - 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 State Street Small/Mid Cap Equity Index Fund (SSMKX). 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	SSMKX	Difference
Sharpe ratio Return per unit of total volatility	2.52	1.88	+0.64
Sortino ratio Return per unit of downside risk	3.42	2.63	+0.79
Omega ratio Gain probability vs. loss probability	1.46	1.32	+0.13
Calmar ratio Return relative to maximum drawdown	3.36	3.16	+0.19
Martin ratio Return relative to average drawdown	15.69	11.48	+4.20
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. SSMKX - Sharpe Ratio Comparison

The current SSSYX Sharpe Ratio is 2.52, which is higher than the SSMKX Sharpe Ratio of 1.88. The chart below compares the historical Sharpe Ratios of SSSYX and SSMKX, 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	SSMKX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	2.52	1.88	+0.64
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.85	0.34	+0.51
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.13	0.56	-0.44
Sharpe Ratio (All Time) Calculated using the full available price history	0.12	0.57	-0.45

Drawdowns

SSSYX vs. SSMKX - Drawdown Comparison

The maximum SSSYX drawdown since its inception was -91.48%, which is greater than SSMKX's maximum drawdown of -41.65%. Use the drawdown chart below to compare losses from any high point for SSSYX and SSMKX.

Drawdown Indicators

	SSSYX	SSMKX	Difference
Max Drawdown Largest peak-to-trough decline	-91.48%	-41.65%	-49.83%
Max Drawdown (1Y) Largest decline over 1 year	-8.88%	-10.03%	+1.15%
Max Drawdown (3Y) Largest decline over 3 years	-18.74%	-26.31%	+7.57%
Max Drawdown (5Y) Largest decline over 5 years	-24.49%	-35.19%	+10.70%
Max Drawdown (10Y) Largest decline over 10 years	-91.48%	-41.65%	-49.83%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-4.15%	-8.70%	+4.55%
Ulcer Index Depth and duration of drawdowns from previous peaks	1.90%	2.76%	-0.86%

Volatility

SSSYX vs. SSMKX - Volatility Comparison

The current volatility for State Street Equity 500 Index Fund Class K (SSSYX) is 2.82%, while State Street Small/Mid Cap Equity Index Fund (SSMKX) has a volatility of 4.70%. This indicates that SSSYX experiences smaller price fluctuations and is considered to be less risky than SSMKX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	SSSYX	SSMKX	Difference
Volatility (1M) Calculated over the trailing 1-month period	2.82%	4.70%	-1.88%
Volatility (6M) Calculated over the trailing 6-month period	8.96%	12.35%	-3.39%
Volatility (1Y) Calculated over the trailing 1-year period	11.85%	16.90%	-5.05%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.88%	22.25%	-5.37%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	124.46%	22.26%	+102.20%

SSSYX vs. SSMKX - Expense Ratio Comparison

SSSYX has a 0.02% expense ratio, which is lower than SSMKX's 0.05% 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

SSSYX vs. SSMKX - Dividend Comparison

SSSYX's dividend yield for the trailing twelve months is around 1.29%, less than SSMKX's 4.47% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
SSMKX State Street Small/Mid Cap Equity Index Fund	4.47%	5.10%	2.12%	2.56%	17.09%	9.69%	1.47%	5.75%	3.68%	5.52%	1.30%	0.00%
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%

Frequently Asked Questions

Can I hold both SSSYX and SSMKX in my portfolio?

SSSYX and SSMKX have a correlation of 0.83, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, SSSYX or SSMKX?

SSMKX has higher volatility (4.70%) compared to SSSYX (2.82%). In terms of maximum drawdown, SSSYX dropped -91.48% vs SSMKX's -41.65%.

Which has better risk-adjusted returns?

SSSYX currently has the higher Sharpe Ratio (2.52 vs 1.88), 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.