FSISX vs. MWNIX

Last updated Jun 4, 2026

FSISX (Fidelity SAI International Small Cap Index Fund) and MWNIX (MFS International New Discovery Fund) are both Foreign Small & Mid Cap Equities funds. Over the past 5 years, FSISX returned 5.61%/yr vs 3.01%/yr for MWNIX. Their correlation of 0.94 suggests significant overlap in exposure. FSISX charges 0.10%/yr vs 1.03%/yr for MWNIX.

Performance

FSISX vs. MWNIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Fidelity SAI International Small Cap Index Fund (FSISX) and MFS International New Discovery Fund (MWNIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, FSISX achieves a 10.30% return, which is significantly higher than MWNIX's 6.86% return.

FSISX

• 1D: -0.09%
• 1M: 2.87%
• YTD: 10.30%
• 6M: 13.47%
• 1Y: 25.30%
• 3Y*: 16.81%
• 5Y*: 5.61%
• 10Y*: —

MWNIX

• 1D: -0.11%
• 1M: 2.42%
• YTD: 6.86%
• 6M: 7.86%
• 1Y: 11.22%
• 3Y*: 10.11%
• 5Y*: 3.01%
• 10Y*: 6.33%

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

FSISX vs. MWNIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021
FSISX Fidelity SAI International Small Cap Index Fund	10.30%	32.61%	1.74%	13.23%	-21.18%	-0.40%
MWNIX MFS International New Discovery Fund	6.86%	16.88%	0.90%	13.03%	-18.63%	0.32%

Correlation

The correlation between FSISX and MWNIX is 0.92, 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	0.92
Correlation (3Y) Calculated over the trailing 3-year period	0.93
Correlation (5Y) Calculated over the trailing 5-year period	0.94
Correlation (All Time) Calculated using the full available price history since May 28, 2021	0.94

The correlation between FSISX and MWNIX has been stable across timeframes, ranging from 0.92 to 0.94 - a consistent structural relationship.

Return for Risk

FSISX vs. MWNIX — Risk / Return Rank

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

FSISX

FSISX Risk / Return Rank: 37
FSISX Sharpe Ratio Rank: 39
FSISX Sortino Ratio Rank: 38
FSISX Omega Ratio Rank: 39
FSISX Calmar Ratio Rank: 31
FSISX Martin Ratio Rank: 35

MWNIX

MWNIX Risk / Return Rank: 11
MWNIX Sharpe Ratio Rank: 12
MWNIX Sortino Ratio Rank: 12
MWNIX Omega Ratio Rank: 12
MWNIX Calmar Ratio Rank: 9
MWNIX Martin Ratio Rank: 11

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.

FSISX vs. MWNIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Fidelity SAI International Small Cap Index Fund (FSISX) and MFS International New Discovery Fund (MWNIX). 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.

	FSISX	MWNIX	Difference
Sharpe ratio: Return per unit of total volatility	1.82	0.93	+0.90
Sortino ratio: Return per unit of downside risk	2.58	1.39	+1.20
Omega ratio: Gain probability vs. loss probability	1.33	1.17	+0.16
Calmar ratio: Return relative to maximum drawdown	2.10	0.90	+1.19
Martin ratio: Return relative to average drawdown	7.81	3.10	+4.71
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

FSISX vs. MWNIX - Sharpe Ratio Comparison

The current FSISX Sharpe Ratio is 1.82, which is higher than the MWNIX Sharpe Ratio of 0.93. The chart below compares the historical Sharpe Ratios of FSISX and MWNIX, 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

	FSISX	MWNIX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.82	0.93	+0.90
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.35	0.23	+0.13
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	—	0.45	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.36	0.58	-0.22

Drawdowns

FSISX vs. MWNIX - Drawdown Comparison

The maximum FSISX drawdown since its inception was -36.84%, smaller than the maximum MWNIX drawdown of -58.38%. Use the drawdown chart below to compare losses from any high point for FSISX and MWNIX.

Drawdown Indicators

	FSISX	MWNIX	Difference
Max Drawdown Largest peak-to-trough decline	-36.84%	-58.38%	+21.54%
Max Drawdown (1Y) Largest decline over 1 year	-11.73%	-11.78%	+0.05%
Max Drawdown (3Y) Largest decline over 3 years	-14.75%	-15.12%	+0.37%
Max Drawdown (5Y) Largest decline over 5 years	-36.84%	-33.67%	-3.17%
Max Drawdown (10Y) Largest decline over 10 years	—	-34.72%	—
Current Drawdown Current decline from peak	-1.29%	-1.69%	+0.40%
Average Drawdown Average peak-to-trough decline	-13.12%	-9.57%	-3.55%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.14%	3.42%	-0.28%

Volatility

FSISX vs. MWNIX - Volatility Comparison

Fidelity SAI International Small Cap Index Fund (FSISX) has a higher volatility of 3.73% compared to MFS International New Discovery Fund (MWNIX) at 3.50%. This indicates that FSISX's price experiences larger fluctuations and is considered to be riskier than MWNIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	FSISX	MWNIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.73%	3.50%	+0.23%
Volatility (6M) Calculated over the trailing 6-month period	10.86%	9.49%	+1.37%
Volatility (1Y) Calculated over the trailing 1-year period	13.52%	11.54%	+1.98%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	15.90%	13.18%	+2.72%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	15.89%	13.99%	+1.90%

FSISX vs. MWNIX - Expense Ratio Comparison

FSISX has a 0.10% expense ratio, which is lower than MWNIX's 1.03% expense ratio.

Dividends

FSISX vs. MWNIX - Dividend Comparison

FSISX's dividend yield for the trailing twelve months is around 3.35%, more than MWNIX's 3.03% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FSISX Fidelity SAI International Small Cap Index Fund	3.35%	3.70%	3.33%	3.13%	3.02%	1.30%	0.00%	0.00%	0.00%	0.00%	0.00%	0.00%
MWNIX MFS International New Discovery Fund	3.03%	3.24%	7.61%	4.05%	5.68%	5.06%	3.90%	2.67%	6.68%	1.63%	1.09%	1.12%

Frequently Asked Questions

Can I hold both FSISX and MWNIX in my portfolio?

With a correlation of 0.92, FSISX and MWNIX 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, FSISX or MWNIX?

FSISX has higher volatility (3.73%) compared to MWNIX (3.50%). In terms of maximum drawdown, FSISX dropped -36.84% vs MWNIX's -58.38%.

Which has better risk-adjusted returns?

FSISX currently has the higher Sharpe Ratio (1.82 vs 0.93), 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.