MFSB vs. MFSM

Last updated Jun 23, 2026

MFSB (MFS Active Core Plus Bond ETF) and MFSM (MFS Active Intermediate Muni Bond ETF) are both exchange-traded funds - MFSB is a Intermediate Core-Plus Bond fund actively managed by MFS, while MFSM is a Municipal Bonds fund actively managed by MFS. Both are actively managed. Over the past year, MFSB returned 5.22% vs 7.16% for MFSM. A 0.72 correlation means they provide meaningful diversification when combined. Both charge a 0.34% expense ratio.

Performance

MFSB vs. MFSM - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in MFS Active Core Plus Bond ETF (MFSB) and MFS Active Intermediate Muni Bond ETF (MFSM). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, MFSB achieves a 0.84% return, which is significantly lower than MFSM's 2.07% return.

MFSB

• 1D: -0.24%
• 1M: 0.91%
• YTD: 0.84%
• 6M: 1.07%
• 1Y: 5.22%
• 3Y*: —
• 5Y*: —
• 10Y*: —

MFSM

• 1D: 0.02%
• 1M: 1.48%
• YTD: 2.07%
• 6M: 2.49%
• 1Y: 7.16%
• 3Y*: —
• 5Y*: —
• 10Y*: —

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

MFSB vs. MFSM - Yearly Performance Comparison

	2026 (YTD)	2025	2024
MFSB MFS Active Core Plus Bond ETF	0.84%	7.40%	-1.28%
MFSM MFS Active Intermediate Muni Bond ETF	2.07%	5.25%	-1.14%

Correlation

The correlation between MFSB and MFSM is 0.69, 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	0.69
Correlation (All Time) Calculated using the full available price history since Dec 5, 2024	0.72

The correlation between MFSB and MFSM has been stable across timeframes, ranging from 0.69 to 0.72 - a consistent structural relationship.

Return for Risk

MFSB vs. MFSM — Risk / Return Rank

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

MFSB

MFSB Risk / Return Rank: 41
MFSB Sharpe Ratio Rank: 43
MFSB Sortino Ratio Rank: 44
MFSB Omega Ratio Rank: 40
MFSB Calmar Ratio Rank: 40
MFSB Martin Ratio Rank: 39

MFSM

MFSM Risk / Return Rank: 77
MFSM Sharpe Ratio Rank: 87
MFSM Sortino Ratio Rank: 92
MFSM Omega Ratio Rank: 92
MFSM Calmar Ratio Rank: 57
MFSM Martin Ratio Rank: 58

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.

MFSB vs. MFSM - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for MFS Active Core Plus Bond ETF (MFSB) and MFS Active Intermediate Muni Bond ETF (MFSM). 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.

	MFSB	MFSM	Difference
Sharpe ratio: Return per unit of total volatility	1.46	2.75	-1.29
Sortino ratio: Return per unit of downside risk	2.16	4.20	-2.04
Omega ratio: Gain probability vs. loss probability	1.25	1.59	-0.34
Calmar ratio: Return relative to maximum drawdown	1.94	2.72	-0.78
Martin ratio: Return relative to average drawdown	5.86	9.99	-4.13

MFSB vs. MFSM - Sharpe Ratio Comparison

The current MFSB Sharpe Ratio is 1.46, which is lower than the MFSM Sharpe Ratio of 2.75. The chart below compares the historical Sharpe Ratios of MFSB and MFSM, 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

MFSB vs. MFSM - Drawdown Comparison

The maximum MFSB drawdown since its inception was -3.19%, smaller than the maximum MFSM drawdown of -3.86%. Use the drawdown chart below to compare losses from any high point for MFSB and MFSM.

Drawdown Indicators

	MFSB	MFSM	Difference
Max Drawdown Largest peak-to-trough decline	-3.19%	-3.86%	+0.67%
Max Drawdown (1Y) Largest decline over 1 year	-2.71%	-2.65%	-0.06%
Current Drawdown Current decline from peak	-0.98%	-0.18%	-0.80%
Average Drawdown Average peak-to-trough decline	-0.83%	-0.86%	+0.03%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.89%	0.72%	+0.17%

Volatility

MFSB vs. MFSM - Volatility Comparison

MFS Active Core Plus Bond ETF (MFSB) has a higher volatility of 1.11% compared to MFS Active Intermediate Muni Bond ETF (MFSM) at 0.71%. This indicates that MFSB's price experiences larger fluctuations and is considered to be riskier than MFSM based on this measure. The chart below showcases a comparison of their rolling one-month volatility.

Volatility by Period

	MFSB	MFSM	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.11%	0.71%	+0.40%
Volatility (6M) Calculated over the trailing 6-month period	2.78%	2.01%	+0.77%
Volatility (1Y) Calculated over the trailing 1-year period	3.59%	2.62%	+0.97%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	4.23%	3.41%	+0.82%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.23%	3.41%	+0.82%

MFSB vs. MFSM - Expense Ratio Comparison

Both MFSB and MFSM have an expense ratio of 0.34%.

Dividends

MFSB vs. MFSM - Dividend Comparison

MFSB's dividend yield for the trailing twelve months is around 4.57%, more than MFSM's 3.54% yield.

Position	TTM	2025	2024
MFSB MFS Active Core Plus Bond ETF	4.57%	4.58%	0.37%
MFSM MFS Active Intermediate Muni Bond ETF	3.54%	3.53%	0.23%

Frequently Asked Questions

Can I hold both MFSB and MFSM in my portfolio?

MFSB and MFSM have a correlation of 0.69, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, MFSB or MFSM?

MFSB has higher volatility (1.11%) compared to MFSM (0.71%). In terms of maximum drawdown, MFSB dropped -3.19% vs MFSM's -3.86%.

Which ETF is better, MFSB or MFSM?

On 1-year performance, MFSM leads with 7.16% vs 5.22% for MFSB. Both ETFs have the same 0.34% expense ratio. On volatility, MFSM has been the lower-risk option at 0.71%. The better choice depends on whether you care most about return, fees, risk, or income.

Which ETF has performed better, MFSB or MFSM?

Over the 1-year period, MFSM has performed better with a 7.16% return vs 5.22%. Past performance does not guarantee future results, so compare this with risk, fees, and fund exposure.

Which ETF is cheaper, MFSB or MFSM?

MFSB and MFSM have the same expense ratio: 0.34% per year.

Which ETF pays a higher dividend yield, MFSB or MFSM?

MFSB has the higher dividend yield at 4.57%, compared with 3.54% for MFSM.

What is the main difference between MFSB and MFSM?

MFSB is categorized as Intermediate Core-Plus Bond, while MFSM is Municipal Bonds.

Which has better risk-adjusted returns?

MFSM currently has the higher Sharpe Ratio (2.75 vs 1.46), 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.