MITTX vs. SSSYX

Last updated Jun 24, 2026

MITTX (MFS Massachusetts Investors Trust) and SSSYX (State Street Equity 500 Index Fund Class K) are both mutual funds - MITTX is a Large Cap Blend Equities fund managed by MFS, while SSSYX is a S&P 500 fund tracking the S&P 500 Index. Over the past 10 years, MITTX returned 13.94%/yr vs 45.70%/yr for SSSYX. With a 0.96 correlation, they move nearly in lockstep. MITTX charges 0.70%/yr vs 0.02%/yr for SSSYX.

Performance

MITTX vs. SSSYX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in MFS Massachusetts Investors Trust (MITTX) and State Street Equity 500 Index Fund Class K (SSSYX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, MITTX achieves a 7.06% return, which is significantly lower than SSSYX's 9.78% return. Over the past 10 years, MITTX has underperformed SSSYX with an annualized return of 13.94%, while SSSYX has yielded a comparatively higher 45.70% annualized return.

MITTX

• 1D: -0.65%
• 1M: 0.11%
• YTD: 7.06%
• 6M: 6.20%
• 1Y: 18.56%
• 3Y*: 16.93%
• 5Y*: 10.03%
• 10Y*: 13.94%

SSSYX

• 1D: -0.36%
• 1M: 0.10%
• YTD: 9.78%
• 6M: 8.78%
• 1Y: 25.47%
• 3Y*: 21.36%
• 5Y*: 13.57%
• 10Y*: 45.70%

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

MITTX vs. SSSYX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
MITTX MFS Massachusetts Investors Trust	7.06%	13.67%	19.69%	19.26%	-16.27%	26.73%	18.72%	31.92%	-5.56%	23.55%
SSSYX State Street Equity 500 Index Fund Class K	9.78%	17.81%	24.99%	26.27%	-18.16%	28.51%	1,083.11%	31.38%	-4.38%	21.61%

Correlation

The correlation between MITTX and SSSYX is 0.95 - 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	0.95
Correlation (3Y) Calculated over the trailing 3-year period	0.96
Correlation (5Y) Calculated over the trailing 5-year period	0.97
Correlation (10Y) Calculated over the trailing 10-year period	0.96
Correlation (All Time) Calculated using the full available price history since Sep 18, 2014	0.96

The correlation between MITTX and SSSYX has been stable across timeframes, ranging from 0.95 to 0.97 - a consistent structural relationship.

Return for Risk

MITTX vs. SSSYX — Risk / Return Rank

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

MITTX

MITTX Risk / Return Rank: 37
MITTX Sharpe Ratio Rank: 39
MITTX Sortino Ratio Rank: 36
MITTX Omega Ratio Rank: 37
MITTX Calmar Ratio Rank: 32
MITTX Martin Ratio Rank: 43

SSSYX

SSSYX Risk / Return Rank: 65
SSSYX Sharpe Ratio Rank: 63
SSSYX Sortino Ratio Rank: 57
SSSYX Omega Ratio Rank: 59
SSSYX Calmar Ratio Rank: 68
SSSYX Martin Ratio Rank: 78

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.

MITTX vs. SSSYX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for MFS Massachusetts Investors Trust (MITTX) and State Street Equity 500 Index Fund Class K (SSSYX). 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.

Values are calculated on a 1-year rolling basis and updated daily. Risk-adjusted metrics are more stable over longer periods — use the period switch above to explore them.

	MITTX	SSSYX	Difference
Sharpe ratio: Return per unit of total volatility	1.68	2.15	-0.47
Sortino ratio: Return per unit of downside risk	2.33	2.91	-0.58
Omega ratio: Gain probability vs. loss probability	1.30	1.39	-0.09
Calmar ratio: Return relative to maximum drawdown	2.02	3.02	-0.99
Martin ratio: Return relative to average drawdown	8.67	13.62	-4.95

MITTX vs. SSSYX - Sharpe Ratio Comparison

The current MITTX Sharpe Ratio is 1.68, which is comparable to the SSSYX Sharpe Ratio of 2.15. The chart below compares the historical Sharpe Ratios of MITTX and SSSYX, calculated using daily returns over the previous 12 months. A higher Sharpe Ratio indicates better risk-adjusted performance relative to the risk-free rate.

Drawdowns

MITTX vs. SSSYX - Drawdown Comparison

The maximum MITTX drawdown since its inception was -49.54%, which is greater than SSSYX's maximum drawdown of -33.77%. Use the drawdown chart below to compare losses from any high point for MITTX and SSSYX.

Drawdown Indicators

	MITTX	SSSYX	Difference
Max Drawdown Largest peak-to-trough decline	-49.54%	-33.77%	-15.77%
Max Drawdown (1Y) Largest decline over 1 year	-9.76%	-8.88%	-0.88%
Max Drawdown (3Y) Largest decline over 3 years	-16.10%	-18.74%	+2.64%
Max Drawdown (5Y) Largest decline over 5 years	-23.27%	-24.49%	+1.22%
Max Drawdown (10Y) Largest decline over 10 years	-33.45%	-33.77%	+0.32%
Current Drawdown Current decline from peak	-1.04%	-1.72%	+0.68%
Average Drawdown Average peak-to-trough decline	-10.53%	-3.91%	-6.62%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.27%	1.96%	+0.31%

Volatility

MITTX vs. SSSYX - Volatility Comparison

The current volatility for MFS Massachusetts Investors Trust (MITTX) is 4.29%, while State Street Equity 500 Index Fund Class K (SSSYX) has a volatility of 4.67%. This indicates that MITTX experiences smaller price fluctuations and is considered to be less risky than SSSYX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	MITTX	SSSYX	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.29%	4.67%	-0.38%
Volatility (6M) Calculated over the trailing 6-month period	9.31%	9.83%	-0.52%
Volatility (1Y) Calculated over the trailing 1-year period	11.75%	12.49%	-0.74%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	15.77%	16.98%	-1.21%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	17.25%	121.18%	-103.93%

MITTX vs. SSSYX - Expense Ratio Comparison

MITTX has a 0.70% expense ratio, which is higher than SSSYX's 0.02% expense ratio.

Dividends

MITTX vs. SSSYX - Dividend Comparison

MITTX's dividend yield for the trailing twelve months is around 13.38%, more than SSSYX's 1.31% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
MITTX MFS Massachusetts Investors Trust	13.38%	14.33%	14.47%	10.96%	9.35%	8.66%	8.14%	7.58%	13.49%	7.27%	5.55%	6.02%
SSSYX State Street Equity 500 Index Fund Class K	1.31%	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 MITTX and SSSYX in my portfolio?

With a correlation of 0.95, MITTX and SSSYX 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, MITTX or SSSYX?

SSSYX has higher volatility (4.67%) compared to MITTX (4.29%). In terms of maximum drawdown, MITTX dropped -49.54% vs SSSYX's -33.77%.

Which has better risk-adjusted returns?

SSSYX currently has the higher Sharpe Ratio (2.15 vs 1.68), 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.