SSMKX vs. PREIX

Last updated Jun 3, 2026

SSMKX (State Street Small/Mid Cap Equity Index Fund) and PREIX (T. Rowe Price Equity Index 500 Fund) are both mutual funds - SSMKX is a Mid Cap Blend Equities fund managed by State Street, while PREIX is a Large Cap Blend Equities fund managed by T. Rowe Price. Over the past 10 years, SSMKX returned 12.36%/yr vs 15.40%/yr for PREIX. Their correlation of 0.86 suggests significant overlap in exposure. SSMKX charges 0.04%/yr vs 0.15%/yr for PREIX.

Performance

SSMKX vs. PREIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in State Street Small/Mid Cap Equity Index Fund (SSMKX) and T. Rowe Price Equity Index 500 Fund (PREIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, SSMKX achieves a 13.04% return, which is significantly higher than PREIX's 11.46% return. Over the past 10 years, SSMKX has underperformed PREIX with an annualized return of 12.36%, while PREIX has yielded a comparatively higher 15.40% annualized return.

SSMKX

• 1D: 0.16%
• 1M: 4.26%
• YTD: 13.04%
• 6M: 13.30%
• 1Y: 30.31%
• 3Y*: 19.97%
• 5Y*: 7.00%
• 10Y*: 12.36%

PREIX

• 1D: 0.27%
• 1M: 5.22%
• YTD: 11.46%
• 6M: 11.82%
• 1Y: 29.32%
• 3Y*: 22.47%
• 5Y*: 13.97%
• 10Y*: 15.40%

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

SSMKX vs. PREIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
SSMKX State Street Small/Mid Cap Equity Index Fund	13.04%	12.77%	17.20%	25.20%	-25.49%	12.38%	32.41%	27.82%	-9.02%	18.16%
PREIX T. Rowe Price Equity Index 500 Fund	11.46%	17.66%	24.78%	26.07%	-18.27%	28.48%	18.17%	31.47%	-4.59%	21.01%

Correlation

The correlation between SSMKX and PREIX 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	0.81
Correlation (5Y) Calculated over the trailing 5-year period	0.85
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 SSMKX and PREIX has been stable across timeframes, ranging from 0.81 to 0.86 - a consistent structural relationship.

Return for Risk

SSMKX vs. PREIX — Risk / Return Rank

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

SSMKX

SSMKX Risk / Return Rank: 45
SSMKX Sharpe Ratio Rank: 38
SSMKX Sortino Ratio Rank: 37
SSMKX Omega Ratio Rank: 34
SSMKX Calmar Ratio Rank: 62
SSMKX Martin Ratio Rank: 54

PREIX

PREIX Risk / Return Rank: 73
PREIX Sharpe Ratio Rank: 76
PREIX Sortino Ratio Rank: 68
PREIX Omega Ratio Rank: 68
PREIX Calmar Ratio Rank: 73
PREIX 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.

SSMKX vs. PREIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for State Street Small/Mid Cap Equity Index Fund (SSMKX) and T. Rowe Price Equity Index 500 Fund (PREIX). 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.

	SSMKX	PREIX	Difference
Sharpe ratio Return per unit of total volatility	1.82	2.53	-0.71
Sortino ratio Return per unit of downside risk	2.56	3.43	-0.88
Omega ratio Gain probability vs. loss probability	1.31	1.46	-0.15
Calmar ratio Return relative to maximum drawdown	3.03	3.34	-0.31
Martin ratio Return relative to average drawdown	11.02	15.63	-4.61
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

SSMKX vs. PREIX - Sharpe Ratio Comparison

The current SSMKX Sharpe Ratio is 1.82, which is comparable to the PREIX Sharpe Ratio of 2.53. The chart below compares the historical Sharpe Ratios of SSMKX and PREIX, 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

	SSMKX	PREIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.82	2.53	-0.71
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.32	0.83	-0.51
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.56	0.85	-0.30
Sharpe Ratio (All Time) Calculated using the full available price history	0.56	0.61	-0.05

Drawdowns

SSMKX vs. PREIX - Drawdown Comparison

The maximum SSMKX drawdown since its inception was -41.65%, smaller than the maximum PREIX drawdown of -55.32%. Use the drawdown chart below to compare losses from any high point for SSMKX and PREIX.

Drawdown Indicators

	SSMKX	PREIX	Difference
Max Drawdown Largest peak-to-trough decline	-41.65%	-55.32%	+13.67%
Max Drawdown (1Y) Largest decline over 1 year	-10.03%	-8.93%	-1.10%
Max Drawdown (3Y) Largest decline over 3 years	-26.31%	-18.78%	-7.53%
Max Drawdown (5Y) Largest decline over 5 years	-35.19%	-24.60%	-10.59%
Max Drawdown (10Y) Largest decline over 10 years	-41.65%	-33.81%	-7.84%
Current Drawdown Current decline from peak	0.00%	0.00%	0.00%
Average Drawdown Average peak-to-trough decline	-8.70%	-8.73%	+0.03%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.76%	1.91%	+0.85%

Volatility

SSMKX vs. PREIX - Volatility Comparison

State Street Small/Mid Cap Equity Index Fund (SSMKX) has a higher volatility of 4.63% compared to T. Rowe Price Equity Index 500 Fund (PREIX) at 2.83%. This indicates that SSMKX's price experiences larger fluctuations and is considered to be riskier than PREIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	SSMKX	PREIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.63%	2.83%	+1.80%
Volatility (6M) Calculated over the trailing 6-month period	12.33%	8.99%	+3.34%
Volatility (1Y) Calculated over the trailing 1-year period	16.91%	11.89%	+5.02%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	22.25%	17.00%	+5.25%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	22.26%	18.11%	+4.15%

SSMKX vs. PREIX - Expense Ratio Comparison

SSMKX has a 0.05% expense ratio, which is lower than PREIX's 0.15% 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

SSMKX vs. PREIX - Dividend Comparison

SSMKX's dividend yield for the trailing twelve months is around 4.51%, more than PREIX's 2.10% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
PREIX T. Rowe Price Equity Index 500 Fund	2.10%	2.32%	1.17%	1.32%	1.50%	1.56%	1.97%	2.13%	2.60%	1.30%	2.03%	2.02%
SSMKX State Street Small/Mid Cap Equity Index Fund	4.51%	5.10%	2.12%	2.56%	17.09%	9.69%	1.47%	5.75%	3.68%	5.52%	1.30%	0.00%

Frequently Asked Questions

Can I hold both SSMKX and PREIX in my portfolio?

SSMKX and PREIX 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, SSMKX or PREIX?

SSMKX has higher volatility (4.63%) compared to PREIX (2.83%). In terms of maximum drawdown, SSMKX dropped -41.65% vs PREIX's -55.32%.

Which has better risk-adjusted returns?

PREIX currently has the higher Sharpe Ratio (2.53 vs 1.82), 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.