COIIX vs. MIDLX

Last updated Jun 4, 2026

COIIX (Calvert International Opportunities Fund) and MIDLX (MFS International New Discovery Fund Class R6) are both Foreign Small & Mid Cap Equities funds. Over the past 10 years, COIIX returned 6.51%/yr vs 6.86%/yr for MIDLX. Their correlation of 0.90 suggests significant overlap in exposure. COIIX charges 1.06%/yr vs 0.91%/yr for MIDLX.

Performance

COIIX vs. MIDLX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in Calvert International Opportunities Fund (COIIX) and MFS International New Discovery Fund Class R6 (MIDLX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, COIIX achieves a 6.38% return, which is significantly lower than MIDLX's 6.95% return. Over the past 10 years, COIIX has underperformed MIDLX with an annualized return of 6.51%, while MIDLX has yielded a comparatively higher 6.86% annualized return.

COIIX

• 1D: 0.00%
• 1M: 2.54%
• YTD: 6.38%
• 6M: 7.98%
• 1Y: 8.04%
• 3Y*: 8.19%
• 5Y*: 0.47%
• 10Y*: 6.51%

MIDLX

• 1D: -0.11%
• 1M: 2.42%
• YTD: 6.95%
• 6M: 7.96%
• 1Y: 11.35%
• 3Y*: 11.09%
• 5Y*: 3.62%
• 10Y*: 6.86%

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

COIIX vs. MIDLX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
COIIX Calvert International Opportunities Fund	6.38%	13.80%	-1.48%	12.95%	-26.69%	13.97%	14.05%	26.09%	-14.57%	38.55%
MIDLX MFS International New Discovery Fund Class R6	6.95%	17.03%	3.33%	13.21%	-18.52%	5.17%	10.15%	24.97%	-10.29%	30.65%

Correlation

The correlation between COIIX and MIDLX is 0.91, 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	0.91
Correlation (3Y) Calculated over the trailing 3-year period	0.91
Correlation (5Y) Calculated over the trailing 5-year period	0.93
Correlation (10Y) Calculated over the trailing 10-year period	0.92
Correlation (All Time) Calculated using the full available price history since Jun 4, 2012	0.90

The correlation between COIIX and MIDLX has been stable across timeframes, ranging from 0.90 to 0.93 - a consistent structural relationship.

Return for Risk

COIIX vs. MIDLX — Risk / Return Rank

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

COIIX

COIIX Risk / Return Rank: 6
COIIX Sharpe Ratio Rank: 6
COIIX Sortino Ratio Rank: 6
COIIX Omega Ratio Rank: 6
COIIX Calmar Ratio Rank: 6
COIIX Martin Ratio Rank: 7

MIDLX

MIDLX Risk / Return Rank: 11
MIDLX Sharpe Ratio Rank: 12
MIDLX Sortino Ratio Rank: 12
MIDLX Omega Ratio Rank: 13
MIDLX Calmar Ratio Rank: 9
MIDLX 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.

COIIX vs. MIDLX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for Calvert International Opportunities Fund (COIIX) and MFS International New Discovery Fund Class R6 (MIDLX). 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.

	COIIX	MIDLX	Difference
Sharpe ratio: Return per unit of total volatility	0.52	0.94	-0.42
Sortino ratio: Return per unit of downside risk	0.84	1.41	-0.57
Omega ratio: Gain probability vs. loss probability	1.10	1.18	-0.07
Calmar ratio: Return relative to maximum drawdown	0.56	0.92	-0.36
Martin ratio: Return relative to average drawdown	1.98	3.17	-1.18
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

COIIX vs. MIDLX - Sharpe Ratio Comparison

The current COIIX Sharpe Ratio is 0.52, which is lower than the MIDLX Sharpe Ratio of 0.94. The chart below compares the historical Sharpe Ratios of COIIX and MIDLX, 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

	COIIX	MIDLX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	0.52	0.94	-0.42
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.03	0.28	-0.25
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.38	0.49	-0.11
Sharpe Ratio (All Time) Calculated using the full available price history	0.23	0.59	-0.36

Drawdowns

COIIX vs. MIDLX - Drawdown Comparison

The maximum COIIX drawdown since its inception was -57.27%, which is greater than MIDLX's maximum drawdown of -34.70%. Use the drawdown chart below to compare losses from any high point for COIIX and MIDLX.

Drawdown Indicators

	COIIX	MIDLX	Difference
Max Drawdown Largest peak-to-trough decline	-57.27%	-34.70%	-22.57%
Max Drawdown (1Y) Largest decline over 1 year	-12.74%	-11.75%	-0.99%
Max Drawdown (3Y) Largest decline over 3 years	-17.12%	-13.15%	-3.97%
Max Drawdown (5Y) Largest decline over 5 years	-40.36%	-33.58%	-6.78%
Max Drawdown (10Y) Largest decline over 10 years	-40.36%	-34.70%	-5.66%
Current Drawdown Current decline from peak	-4.78%	-1.64%	-3.14%
Average Drawdown Average peak-to-trough decline	-14.98%	-6.92%	-8.06%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.62%	3.41%	+0.21%

Volatility

COIIX vs. MIDLX - Volatility Comparison

Calvert International Opportunities Fund (COIIX) and MFS International New Discovery Fund Class R6 (MIDLX) have volatilities of 3.56% and 3.48%, 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

	COIIX	MIDLX	Difference
Volatility (1M) Calculated over the trailing 1-month period	3.56%	3.48%	+0.08%
Volatility (6M) Calculated over the trailing 6-month period	11.03%	9.46%	+1.57%
Volatility (1Y) Calculated over the trailing 1-year period	13.76%	11.52%	+2.24%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.97%	13.21%	+3.76%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	17.00%	14.01%	+2.99%

COIIX vs. MIDLX - Expense Ratio Comparison

COIIX has a 1.06% expense ratio, which is higher than MIDLX's 0.91% expense ratio.

Dividends

COIIX vs. MIDLX - Dividend Comparison

COIIX's dividend yield for the trailing twelve months is around 3.28%, more than MIDLX's 3.15% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
COIIX Calvert International Opportunities Fund	3.28%	3.49%	3.24%	1.77%	0.61%	7.67%	0.78%	1.32%	9.82%	7.19%	1.52%	4.53%
MIDLX MFS International New Discovery Fund Class R6	3.15%	3.37%	10.08%	4.21%	5.85%	5.19%	4.03%	4.36%	6.82%	1.63%	1.09%	1.25%

Frequently Asked Questions

Can I hold both COIIX and MIDLX in my portfolio?

With a correlation of 0.91, COIIX and MIDLX 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, COIIX or MIDLX?

COIIX has higher volatility (3.56%) compared to MIDLX (3.48%). In terms of maximum drawdown, COIIX dropped -57.27% vs MIDLX's -34.70%.

Which has better risk-adjusted returns?

MIDLX currently has the higher Sharpe Ratio (0.94 vs 0.52), 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.