MFSI vs. BUFI

Last updated Jun 4, 2026

MFSI (MFS Active International ETF) and BUFI (AB International Buffer ETF) are both exchange-traded funds - MFSI is a Foreign Large Cap Equities fund actively managed by MFS, while BUFI is a Defined Outcome fund actively managed by AllianceBernstein. Both are actively managed. Over the past year, MFSI returned 17.49% vs 12.80% for BUFI. Their correlation of 0.92 suggests significant overlap in exposure. MFSI charges 0.59%/yr vs 0.69%/yr for BUFI.

Performance

MFSI vs. BUFI - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in MFS Active International ETF (MFSI) and AB International Buffer ETF (BUFI). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, MFSI achieves a 6.73% return, which is significantly higher than BUFI's 4.92% return.

MFSI

• 1D: -1.16%
• 1M: 5.04%
• YTD: 6.73%
• 6M: 9.01%
• 1Y: 17.49%
• 3Y*: —
• 5Y*: —
• 10Y*: —

BUFI

• 1D: -0.31%
• 1M: 1.83%
• YTD: 4.92%
• 6M: 6.32%
• 1Y: 12.80%
• 3Y*: —
• 5Y*: —
• 10Y*: —

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

MFSI vs. BUFI - Yearly Performance Comparison

	2026 (YTD)	2025	2024
MFSI MFS Active International ETF	6.73%	26.43%	-3.76%
BUFI AB International Buffer ETF	4.92%	16.50%	-1.31%

Correlation

The correlation between MFSI and BUFI is 0.93, 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	0.93
Correlation (All Time) Calculated using the full available price history since Dec 11, 2024	0.92

The correlation between MFSI and BUFI has been stable across timeframes, ranging from 0.92 to 0.93 - a consistent structural relationship.

Return for Risk

MFSI vs. BUFI — Risk / Return Rank

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

MFSI

MFSI Risk / Return Rank: 34
MFSI Sharpe Ratio Rank: 34
MFSI Sortino Ratio Rank: 33
MFSI Omega Ratio Rank: 33
MFSI Calmar Ratio Rank: 33
MFSI Martin Ratio Rank: 38

BUFI

BUFI Risk / Return Rank: 47
BUFI Sharpe Ratio Rank: 44
BUFI Sortino Ratio Rank: 46
BUFI Omega Ratio Rank: 47
BUFI Calmar Ratio Rank: 46
BUFI Martin Ratio Rank: 53

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.

MFSI vs. BUFI - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for MFS Active International ETF (MFSI) and AB International Buffer ETF (BUFI). 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.

	MFSI	BUFI	Difference
Sharpe ratio: Return per unit of total volatility	1.20	1.53	-0.32
Sortino ratio: Return per unit of downside risk	1.74	2.25	-0.50
Omega ratio: Gain probability vs. loss probability	1.22	1.30	-0.08
Calmar ratio: Return relative to maximum drawdown	1.57	2.26	-0.69
Martin ratio: Return relative to average drawdown	5.89	8.98	-3.10
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

MFSI vs. BUFI - Sharpe Ratio Comparison

The current MFSI Sharpe Ratio is 1.20, which is comparable to the BUFI Sharpe Ratio of 1.53. The chart below compares the historical Sharpe Ratios of MFSI and BUFI, 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

	MFSI	BUFI	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.20	1.53	-0.32
Sharpe Ratio (All Time) Calculated using the full available price history	1.17	1.50	-0.33

Drawdowns

MFSI vs. BUFI - Drawdown Comparison

The maximum MFSI drawdown since its inception was -13.67%, which is greater than BUFI's maximum drawdown of -7.43%. Use the drawdown chart below to compare losses from any high point for MFSI and BUFI.

Drawdown Indicators

	MFSI	BUFI	Difference
Max Drawdown Largest peak-to-trough decline	-13.67%	-7.43%	-6.24%
Max Drawdown (1Y) Largest decline over 1 year	-11.17%	-5.69%	-5.48%
Current Drawdown Current decline from peak	-1.16%	-0.32%	-0.84%
Average Drawdown Average peak-to-trough decline	-1.97%	-0.86%	-1.11%
Ulcer Index Depth and duration of drawdowns from previous peaks	2.98%	1.43%	+1.55%

Volatility

MFSI vs. BUFI - Volatility Comparison

MFS Active International ETF (MFSI) has a higher volatility of 4.72% compared to AB International Buffer ETF (BUFI) at 2.20%. This indicates that MFSI's price experiences larger fluctuations and is considered to be riskier than BUFI based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	MFSI	BUFI	Difference
Volatility (1M) Calculated over the trailing 1-month period	4.72%	2.20%	+2.52%
Volatility (6M) Calculated over the trailing 6-month period	12.16%	7.05%	+5.11%
Volatility (1Y) Calculated over the trailing 1-year period	14.62%	8.43%	+6.19%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	16.32%	9.15%	+7.17%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	16.32%	9.15%	+7.17%

MFSI vs. BUFI - Expense Ratio Comparison

MFSI has a 0.59% expense ratio, which is lower than BUFI's 0.69% expense ratio.

Dividends

MFSI vs. BUFI - Dividend Comparison

MFSI's dividend yield for the trailing twelve months is around 0.76%, while BUFI has not paid dividends to shareholders.

Position	TTM	2025
BUFI AB International Buffer ETF	0.00%	0.00%
MFSI MFS Active International ETF	0.76%	0.81%

Frequently Asked Questions

Can I hold both MFSI and BUFI in my portfolio?

With a correlation of 0.93, MFSI and BUFI 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, MFSI or BUFI?

MFSI has higher volatility (4.72%) compared to BUFI (2.20%). In terms of maximum drawdown, MFSI dropped -13.67% vs BUFI's -7.43%.

Which ETF is better, MFSI or BUFI?

On 1-year performance, MFSI leads with 17.49% vs 12.80% for BUFI. On fees, MFSI is cheaper at 0.59% per year. On volatility, BUFI has been the lower-risk option at 2.20%. The better choice depends on whether you care most about return, fees, risk, or income.

Which ETF has performed better, MFSI or BUFI?

Over the 1-year period, MFSI has performed better with a 17.49% return vs 12.80%. Past performance does not guarantee future results, so compare this with risk, fees, and fund exposure.

Which ETF is cheaper, MFSI or BUFI?

MFSI is cheaper with a 0.59% expense ratio, compared with 0.69% for BUFI.

Which ETF pays a higher dividend yield, MFSI or BUFI?

MFSI has the higher dividend yield at 0.76%, compared with 0.00% for BUFI.

What is the main difference between MFSI and BUFI?

MFSI is categorized as Foreign Large Cap Equities, while BUFI is Defined Outcome. They also come from different issuers: MFS and AllianceBernstein. Their fees differ too: 0.59% for MFSI and 0.69% for BUFI.

Which has better risk-adjusted returns?

BUFI currently has the higher Sharpe Ratio (1.53 vs 1.20), 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.