MAILX vs. KGIIX

Last updated Jun 24, 2026

MAILX (BlackRock International Fund of BlackRock Series, Inc.) and KGIIX (Kopernik International Fund) are both Foreign Large Cap Equities funds. Over the past 10 years, MAILX returned 8.86%/yr vs 9.34%/yr for KGIIX. A 0.55 correlation means they provide meaningful diversification when combined. MAILX charges 0.65%/yr vs 1.04%/yr for KGIIX.

Performance

MAILX vs. KGIIX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in BlackRock International Fund of BlackRock Series, Inc. (MAILX) and Kopernik International Fund (KGIIX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, MAILX achieves a 12.55% return, which is significantly higher than KGIIX's 4.07% return. Over the past 10 years, MAILX has underperformed KGIIX with an annualized return of 8.86%, while KGIIX has yielded a comparatively higher 9.34% annualized return.

MAILX

• 1D: -0.12%
• 1M: 3.19%
• YTD: 12.55%
• 6M: 12.75%
• 1Y: 23.65%
• 3Y*: 12.05%
• 5Y*: 2.52%
• 10Y*: 8.86%

KGIIX

• 1D: -1.10%
• 1M: -4.28%
• YTD: 4.07%
• 6M: 3.46%
• 1Y: 25.88%
• 3Y*: 17.40%
• 5Y*: 8.08%
• 10Y*: 9.34%

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

MAILX vs. KGIIX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
MAILX BlackRock International Fund of BlackRock Series, Inc.	12.55%	15.60%	0.46%	19.67%	-24.24%	9.32%	21.82%	31.77%	-21.45%	31.87%
KGIIX Kopernik International Fund	4.07%	54.97%	-7.01%	13.86%	-14.05%	16.62%	18.94%	16.37%	-6.24%	10.50%

Correlation

The correlation between MAILX and KGIIX is 0.57, which is moderate. They share some common price drivers but move independently often enough to provide real diversification benefit when combined.

	Correlation
Correlation (1Y) Calculated over the trailing 1-year period	0.57
Correlation (3Y) Calculated over the trailing 3-year period	0.44
Correlation (5Y) Calculated over the trailing 5-year period	0.58
Correlation (10Y) Calculated over the trailing 10-year period	0.55
Correlation (All Time) Calculated using the full available price history since Jan 4, 2016	0.55

The correlation between MAILX and KGIIX shifts across timeframes, from 0.44 (3 years) to 0.58 (5 years), reflecting how their relationship changes across market environments.

Return for Risk

MAILX vs. KGIIX — Risk / Return Rank

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

MAILX

MAILX Risk / Return Rank: 33
MAILX Sharpe Ratio Rank: 33
MAILX Sortino Ratio Rank: 32
MAILX Omega Ratio Rank: 33
MAILX Calmar Ratio Rank: 32
MAILX Martin Ratio Rank: 35

KGIIX

KGIIX Risk / Return Rank: 53
KGIIX Sharpe Ratio Rank: 57
KGIIX Sortino Ratio Rank: 48
KGIIX Omega Ratio Rank: 53
KGIIX Calmar Ratio Rank: 63
KGIIX Martin Ratio Rank: 42

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.

MAILX vs. KGIIX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for BlackRock International Fund of BlackRock Series, Inc. (MAILX) and Kopernik International Fund (KGIIX). 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.

	MAILX	KGIIX	Difference
Sharpe ratio: Return per unit of total volatility	1.55	2.05	-0.50
Sortino ratio: Return per unit of downside risk	2.18	2.68	-0.50
Omega ratio: Gain probability vs. loss probability	1.28	1.37	-0.08
Calmar ratio: Return relative to maximum drawdown	1.98	2.92	-0.94
Martin ratio: Return relative to average drawdown	7.39	8.47	-1.08

MAILX vs. KGIIX - Sharpe Ratio Comparison

The current MAILX Sharpe Ratio is 1.55, which is comparable to the KGIIX Sharpe Ratio of 2.05. The chart below compares the historical Sharpe Ratios of MAILX and KGIIX, 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

MAILX vs. KGIIX - Drawdown Comparison

The maximum MAILX drawdown since its inception was -59.57%, which is greater than KGIIX's maximum drawdown of -27.81%. Use the drawdown chart below to compare losses from any high point for MAILX and KGIIX.

Drawdown Indicators

	MAILX	KGIIX	Difference
Max Drawdown Largest peak-to-trough decline	-59.57%	-27.81%	-31.76%
Max Drawdown (1Y) Largest decline over 1 year	-12.34%	-9.27%	-3.07%
Max Drawdown (3Y) Largest decline over 3 years	-17.36%	-13.58%	-3.78%
Max Drawdown (5Y) Largest decline over 5 years	-41.68%	-27.81%	-13.87%
Max Drawdown (10Y) Largest decline over 10 years	-41.68%	-27.81%	-13.87%
Current Drawdown Current decline from peak	-0.20%	-9.27%	+9.07%
Average Drawdown Average peak-to-trough decline	-16.11%	-6.11%	-10.00%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.30%	3.19%	+0.11%

Volatility

MAILX vs. KGIIX - Volatility Comparison

BlackRock International Fund of BlackRock Series, Inc. (MAILX) has a higher volatility of 6.18% compared to Kopernik International Fund (KGIIX) at 3.77%. This indicates that MAILX's price experiences larger fluctuations and is considered to be riskier than KGIIX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	MAILX	KGIIX	Difference
Volatility (1M) Calculated over the trailing 1-month period	6.18%	3.77%	+2.41%
Volatility (6M) Calculated over the trailing 6-month period	13.58%	10.77%	+2.81%
Volatility (1Y) Calculated over the trailing 1-year period	15.84%	13.22%	+2.62%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	18.02%	13.27%	+4.75%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	18.38%	12.66%	+5.72%

MAILX vs. KGIIX - Expense Ratio Comparison

MAILX has a 0.65% expense ratio, which is lower than KGIIX's 1.04% expense ratio.

Dividends

MAILX vs. KGIIX - Dividend Comparison

MAILX's dividend yield for the trailing twelve months is around 1.59%, less than KGIIX's 13.71% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
KGIIX Kopernik International Fund	13.71%	14.26%	0.48%	12.56%	2.46%	5.77%	2.89%	2.50%	1.19%	1.35%	0.33%	0.00%
MAILX BlackRock International Fund of BlackRock Series, Inc.	1.59%	1.79%	0.90%	1.08%	1.13%	7.30%	0.33%	1.11%	1.83%	1.39%	1.62%	0.65%

Frequently Asked Questions

Can I hold both MAILX and KGIIX in my portfolio?

MAILX and KGIIX have a correlation of 0.57, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, MAILX or KGIIX?

MAILX has higher volatility (6.18%) compared to KGIIX (3.77%). In terms of maximum drawdown, MAILX dropped -59.57% vs KGIIX's -27.81%.

Which has better risk-adjusted returns?

KGIIX currently has the higher Sharpe Ratio (2.05 vs 1.55), 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.