MRBIX vs. LMSMX

Last updated Jun 4, 2026

MRBIX (MFS Total Return Bond Fund) and LMSMX (Western Asset SMASh Series M Fund) are both Intermediate Core-Plus Bond funds. Over the past 5 years, MRBIX returned 0.23%/yr vs -1.89%/yr for LMSMX. Their correlation of 0.84 suggests significant overlap in exposure. MRBIX charges 0.45%/yr vs 0.00%/yr for LMSMX.

Performance

MRBIX vs. LMSMX - Performance Comparison

The chart below illustrates the hypothetical performance of a $10,000 investment in MFS Total Return Bond Fund (MRBIX) and Western Asset SMASh Series M Fund (LMSMX). The values are adjusted to include any dividend payments, if applicable.

Returns By Period

In the year-to-date period, MRBIX achieves a 0.52% return, which is significantly lower than LMSMX's 1.11% return.

MRBIX

• 1D: 0.00%
• 1M: 0.55%
• YTD: 0.52%
• 6M: 0.48%
• 1Y: 5.67%
• 3Y*: 4.35%
• 5Y*: 0.23%
• 10Y*: 1.97%

LMSMX

• 1D: 0.00%
• 1M: 0.23%
• YTD: 1.11%
• 6M: 1.33%
• 1Y: 8.61%
• 3Y*: 4.81%
• 5Y*: -1.89%
• 10Y*: —

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

MRBIX vs. LMSMX - Yearly Performance Comparison

	2026 (YTD)	2025	2024	2023	2022	2021	2020	2019	2018	2017
MRBIX MFS Total Return Bond Fund	0.52%	7.35%	1.77%	6.45%	-14.52%	-0.84%	8.83%	9.96%	-1.03%	3.90%
LMSMX Western Asset SMASh Series M Fund	1.11%	12.15%	-1.72%	5.13%	-23.44%	-2.32%	12.86%	7.71%	1.46%	5.52%

Correlation

The correlation between MRBIX and LMSMX is 0.84, 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	0.84
Correlation (3Y) Calculated over the trailing 3-year period	0.89
Correlation (5Y) Calculated over the trailing 5-year period	0.89
Correlation (All Time) Calculated using the full available price history since Feb 2, 2017	0.84

The correlation between MRBIX and LMSMX has been stable across timeframes, ranging from 0.84 to 0.89 - a consistent structural relationship.

Return for Risk

MRBIX vs. LMSMX — Risk / Return Rank

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

MRBIX

MRBIX Risk / Return Rank: 27
MRBIX Sharpe Ratio Rank: 27
MRBIX Sortino Ratio Rank: 29
MRBIX Omega Ratio Rank: 26
MRBIX Calmar Ratio Rank: 30
MRBIX Martin Ratio Rank: 25

LMSMX

LMSMX Risk / Return Rank: 43
LMSMX Sharpe Ratio Rank: 31
LMSMX Sortino Ratio Rank: 36
LMSMX Omega Ratio Rank: 36
LMSMX Calmar Ratio Rank: 71
LMSMX Martin Ratio Rank: 41

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.

MRBIX vs. LMSMX - Risk-Adjusted Trends Comparison

This table presents a comparison of risk-adjusted performance metrics for MFS Total Return Bond Fund (MRBIX) and Western Asset SMASh Series M Fund (LMSMX). 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.

	MRBIX	LMSMX	Difference
Sharpe ratio: Return per unit of total volatility	1.48	1.61	-0.12
Sortino ratio: Return per unit of downside risk	2.24	2.50	-0.26
Omega ratio: Gain probability vs. loss probability	1.27	1.32	-0.05
Calmar ratio: Return relative to maximum drawdown	2.06	3.28	-1.22
Martin ratio: Return relative to average drawdown	6.03	8.74	-2.72
Data is calculated on a 1-year rolling basis and updated daily. The trend shows the change in the indicator over the past month.

MRBIX vs. LMSMX - Sharpe Ratio Comparison

The current MRBIX Sharpe Ratio is 1.48, which is comparable to the LMSMX Sharpe Ratio of 1.61. The chart below compares the historical Sharpe Ratios of MRBIX and LMSMX, 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

	MRBIX	LMSMX	Difference
Sharpe Ratio (1Y) Calculated over the trailing 1-year period	1.48	1.61	-0.12
Sharpe Ratio (5Y) Calculated over the trailing 5-year period	0.04	-0.18	+0.22
Sharpe Ratio (10Y) Calculated over the trailing 10-year period	0.40	—	—
Sharpe Ratio (All Time) Calculated using the full available price history	0.97	0.17	+0.80

Drawdowns

MRBIX vs. LMSMX - Drawdown Comparison

The maximum MRBIX drawdown since its inception was -19.25%, smaller than the maximum LMSMX drawdown of -30.76%. Use the drawdown chart below to compare losses from any high point for MRBIX and LMSMX.

Drawdown Indicators

	MRBIX	LMSMX	Difference
Max Drawdown Largest peak-to-trough decline	-19.25%	-30.76%	+11.51%
Max Drawdown (1Y) Largest decline over 1 year	-2.77%	-2.64%	-0.13%
Max Drawdown (3Y) Largest decline over 3 years	-6.29%	-10.50%	+4.21%
Max Drawdown (5Y) Largest decline over 5 years	-19.25%	-30.18%	+10.93%
Max Drawdown (10Y) Largest decline over 10 years	-19.25%	—	—
Current Drawdown Current decline from peak	-1.29%	-12.55%	+11.26%
Average Drawdown Average peak-to-trough decline	-2.47%	-10.12%	+7.65%
Ulcer Index Depth and duration of drawdowns from previous peaks	0.94%	0.99%	-0.05%

Volatility

MRBIX vs. LMSMX - Volatility Comparison

MFS Total Return Bond Fund (MRBIX) and Western Asset SMASh Series M Fund (LMSMX) have volatilities of 1.35% and 1.31%, 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

	MRBIX	LMSMX	Difference
Volatility (1M) Calculated over the trailing 1-month period	1.35%	1.31%	+0.04%
Volatility (6M) Calculated over the trailing 6-month period	2.73%	2.68%	+0.05%
Volatility (1Y) Calculated over the trailing 1-year period	3.86%	5.41%	-1.55%
Volatility (5Y) Calculated over the trailing 5-year period, annualized	5.73%	10.38%	-4.65%
Volatility (10Y) Calculated over the trailing 10-year period, annualized	4.92%	8.16%	-3.24%

MRBIX vs. LMSMX - Expense Ratio Comparison

MRBIX has a 0.45% expense ratio, which is higher than LMSMX's 0.00% expense ratio.

Dividends

MRBIX vs. LMSMX - Dividend Comparison

MRBIX's dividend yield for the trailing twelve months is around 4.17%, less than LMSMX's 4.40% yield.

Position	TTM	2025	2024	2023	2022	2021	2020	2019	2018	2017	2016	2015
LMSMX Western Asset SMASh Series M Fund	4.40%	4.20%	5.24%	4.68%	3.40%	3.78%	6.84%	7.19%	3.18%	3.24%	0.00%	0.00%
MRBIX MFS Total Return Bond Fund	4.17%	4.21%	3.69%	3.42%	2.39%	3.42%	3.00%	3.06%	2.87%	2.65%	3.02%	3.76%

Frequently Asked Questions

Can I hold both MRBIX and LMSMX in my portfolio?

MRBIX and LMSMX have a correlation of 0.84, meaning they provide meaningful diversification benefit when combined. Depending on your allocation goals, holding both could reduce overall portfolio risk.

Which is riskier, MRBIX or LMSMX?

MRBIX has higher volatility (1.35%) compared to LMSMX (1.31%). In terms of maximum drawdown, MRBIX dropped -19.25% vs LMSMX's -30.76%.

Which has better risk-adjusted returns?

LMSMX currently has the higher Sharpe Ratio (1.61 vs 1.48), 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.