MAILX vs. FAOSX

Last updated Jun 3, 2026

MAILX (BlackRock International Fund of BlackRock Series, Inc.) and FAOSX (Fidelity Advisor Overseas Fund Class Z) are both Foreign Large Cap Equities funds. Over the past 5 years, MAILX returned 2.10%/yr vs 3.67%/yr for FAOSX. Their correlation of 0.86 suggests significant overlap in exposure. MAILX charges 0.65%/yr vs 1.02%/yr for FAOSX.

Performance

MAILX vs. FAOSX - Performance Comparison

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

Returns By Period

MAILX

• 1D: 0.73%
• 1M: 6.27%
• YTD: 11.69%
• 6M: 14.93%
• 1Y: 20.59%
• 3Y*: 11.91%
• 5Y*: 2.10%
• 10Y*: 7.96%

FAOSX

• 1D: 0.00%
• 1M: 0.00%
• YTD: 0.00%
• 6M: 0.00%
• 1Y: -2.18%
• 3Y*: 8.88%
• 5Y*: 3.67%
• 10Y*: —

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

MAILX vs. FAOSX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
MAILX BlackRock International Fund of BlackRock Series, Inc.	11.69%	15.60%	0.46%	19.67%	-24.24%	9.32%	21.82%	31.77%	-21.45%	27.75%
FAOSX Fidelity Advisor Overseas Fund Class Z	0.00%	15.36%	5.06%	20.52%	-24.31%	19.42%	15.17%	27.96%	-14.73%	26.25%

Correlation

The correlation between MAILX and FAOSX is 0.53, 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	0.53
Correlation (3Y) Calculated over the trailing 3-year period	0.78
Correlation (5Y) Calculated over the trailing 5-year period	0.85
Correlation (All Time) Calculated using the full available price history since Feb 2, 2017	0.86

Over the past year, the correlation between MAILX and FAOSX has dropped to 0.53 - well below their long-term average of 0.86, suggesting their price drivers have been diverging.

Return for Risk

MAILX vs. FAOSX — Risk / Return Rank

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

MAILX

MAILX Risk / Return Rank: 24
MAILX Sharpe Ratio Rank: 24
MAILX Sortino Ratio Rank: 23
MAILX Omega Ratio Rank: 24
MAILX Calmar Ratio Rank: 21
MAILX Martin Ratio Rank: 25

FAOSX

FAOSX Risk / Return Rank: 5
FAOSX Sharpe Ratio Rank: 2
FAOSX Sortino Ratio Rank: 2
FAOSX Omega Ratio Rank: 2
FAOSX Calmar Ratio Rank: 13
FAOSX Martin Ratio Rank: 7

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. FAOSX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for BlackRock International Fund of BlackRock Series, Inc. (MAILX) and Fidelity Advisor Overseas Fund Class Z (FAOSX). 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.

	MAILX	FAOSX	Difference
Sharpe ratio Return per unit of total volatility	1.43	-0.18	+1.61
Sortino ratio Return per unit of downside risk	2.04	-0.18	+2.22
Omega ratio Gain probability vs. loss probability	1.26	0.97	+0.29
Calmar ratio Return relative to maximum drawdown	1.71	1.25	+0.47
Martin ratio Return relative to average drawdown	6.38	2.29	+4.09
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

MAILX vs. FAOSX - Sharpe Ratio Comparison

The current MAILX Sharpe Ratio is 1.43, which is higher than the FAOSX Sharpe Ratio of -0.18. The chart below compares the historical Sharpe Ratios of MAILX and FAOSX, 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

	MAILX	FAOSX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.43	-0.18	+1.61
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.12	0.23	-0.11
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.44	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.24	0.50	-0.26

Drawdowns

MAILX vs. FAOSX - Drawdown Comparison

The maximum MAILX drawdown since its inception was -59.57%, which is greater than FAOSX's maximum drawdown of -36.24%. Use the drawdown chart below to compare losses from any high point for MAILX and FAOSX.

Drawdown Indicators

	MAILX	FAOSX	Difference
Max Drawdown Largest peak-to-trough decline	-59.57%	-36.24%	-23.33%
Max Drawdown (1Y) Largest decline over 1 year	-12.34%	-7.26%	-5.08%
Max Drawdown (3Y) Largest decline over 3 years	-17.36%	-13.96%	-3.40%
Max Drawdown (5Y) Largest decline over 5 years	-41.68%	-36.24%	-5.44%
Max Drawdown (10Y) Largest decline over 10 years	-41.68%	—	—
Current Drawdown Current decline from peak	0.00%	-5.86%	+5.86%
Average Drawdown Average peak-to-trough decline	-16.14%	-7.93%	-8.21%
Ulcer Index Depth and duration of drawdowns from previous peaks	3.31%	3.95%	-0.64%

Volatility

MAILX vs. FAOSX - Volatility Comparison

BlackRock International Fund of BlackRock Series, Inc. (MAILX) has a higher volatility of 5.56% compared to Fidelity Advisor Overseas Fund Class Z (FAOSX) at 0.00%. This indicates that MAILX's price experiences larger fluctuations and is considered to be riskier than FAOSX based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	MAILX	FAOSX	Difference
Volatility (1M) Calculated over the trailing 1-month period	5.56%	0.00%	+5.56%
Volatility (6M) Calculated over the trailing 6-month period	12.45%	4.08%	+8.37%
Volatility (1Y) Calculated over the trailing 1-year period	14.98%	9.20%	+5.78%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	17.87%	16.72%	+1.15%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	18.36%	16.68%	+1.68%

MAILX vs. FAOSX - Expense Ratio Comparison

MAILX has a 0.65% expense ratio, which is lower than FAOSX's 1.02% expense ratio.

Dividends

MAILX vs. FAOSX - Dividend Comparison

MAILX's dividend yield for the trailing twelve months is around 1.61%, less than FAOSX's 8.67% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
FAOSX Fidelity Advisor Overseas Fund Class Z	8.67%	8.67%	1.80%	1.12%	0.85%	2.07%	0.00%	1.70%	5.30%	3.93%	0.00%	0.00%
MAILX BlackRock International Fund of BlackRock Series, Inc.	1.61%	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 FAOSX in my portfolio?

MAILX and FAOSX have a correlation of 0.53, 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 FAOSX?

MAILX has higher volatility (5.56%) compared to FAOSX (0.00%). In terms of maximum drawdown, MAILX dropped -59.57% vs FAOSX's -36.24%.

Which has better risk-adjusted returns?

MAILX currently has the higher Sharpe Ratio (1.43 vs -0.18), 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.