Fund Evaluator:
MFS Total Return Bond R6 (MRBKX)
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Best Performing in Intermediate Core-Plus Bond Over the Last Year
| 4.1% | Diamond Hill Core Plus Bond Y (DHNYX) |
| 3.9% | Diamond Hill Core Plus Bond I (DHNIX) |
| 3.7% | Diamond Hill Core Plus Bond Investor (DHNAX) |
| 3.5% | Weitz Core Plus Income Investor (WCPNX) |
| 3.4% | Nuveen Core Plus Bond I (TCBHX) |
Fund Details
MFS Total Return Bond R6 Overview
MFS Total Return Bond R6 (MRBKX) is an actively managed Taxable Bond Intermediate Core-Plus Bond fund. MFS launched the fund in 2006.
The investment seeks total return with an emphasis on current income but also considering capital appreciation. The fund normally invests at least 80% of its net assets in debt instruments. Debt instruments include corporate bonds, U.S. government securities, foreign government securities, securitized instruments, municipal instruments and other obligations to repay money borrowed. It primarily invests the fund's assets in investment grade quality debt instruments, but may also invest in below investment grade quality debt instruments.
About MFS Total Return Bond R6 (MRBKX)
There are 2 members of the management team with an average tenure of 11.59 years: Joshua Marston (2009), Alexander Mackey (2019). Management tenure is more important for actively managed funds than passive index funds.
The fund has 1 primary benchmark: Bloomberg US Agg Bond TR USD index with a weighting of 100%. MFS Total Return Bond R6 has 1083 securities in its portfolio. The top 10 holdings constitute 25.2% of the fund’s assets. The fund meets the SEC requirement of being classified as a diversified fund. The fund is not considered to have an ESG focus with its investment selection and management.
MFS Total Return Bond R6 is part of the Fixed Income global asset class and is within the Taxable Bond fund group. MFS Total Return Bond R6 has 11.6% of its portfolio invested in foreign issues. The overall assets allocated to domestic stock is 0.0%. There is 0.0% allocated to foreign stock, and 1.2% is allocated to preferred stocks. The bond allocation as a percentage of total assets is 113.1% (101.5% domestic bond, 11.6% foreign bond and 0.0% convertible bond). MFS Total Return Bond R6 has -14.2% of the portfolio in cash.
Assets Under Management
The fund has $3 billion in total assets, which is above the $1 billion average for the Intermediate Core-Plus Bond category. Normally, lower assets under management translates to higher average expense ratios, and greater total assets are desired. However, for some investment categories, such as small-cap investing, it may be difficult for the manager to fully employ the desired active strategy if assets grow too large or too quickly.
MRBKX Performance and Fees
The expense ratio measures how much of a fund’s assets are used for administrative expenses and operating expenses, including adviser fees and fees for the transfer agent and custodial services. The MFS Total Return Bond R6 expense ratio is below average compared to funds in the Intermediate Core-Plus Bond category. MFS Total Return Bond R6 has an expense ratio of 0.36%, which is 54% lower than its category average, making the fund expense ratio grade a A. While it is difficult to predict returns, it is known that high annual expense ratios reduce your rate of return, and excessive fees are difficult to overcome. Active management normally comes with higher expense ratios than passive index management. Certain investment categories such as small company and foreign also normally have higher expense ratios. It is best to compare fund expense ratios against the category averages for meaningful assessments.
High portfolio turnover can translate to higher expenses and lower aftertax returns. MFS Total Return Bond R6 has a portfolio turnover rate of 75%, indicating that holds its assets around 0.0 years. By way of comparison, the average portfolio turnover is 181% for the Intermediate Core-Plus Bond category.
Recently, in the month of July 2026, MFS Total Return Bond R6 returned -1.3%, which earned it a grade of C, as the Intermediate Core-Plus Bond category had an average return of -1.3%. The letter grades of A, B, C, D and F are based upon relative rankings within the investment category. A grade of A, for example, would indicate that the return is in the highest 20% for that time period compared to all funds in that category.
MFS Total Return Bond R6 has a trailing yield of 4.31%, which is below the 4.36% category average. The fund normally distributes its income monthly and its capital gains annually.
It’s natural to seek the best-performing investments, but you must consider the relationship between risk and return and the impact of costs and taxes on your realized returns.
MFS Total Return Bond R6 Grades
Year to date, the fund has returned -0.3%, 0.3 percentage points better than the category, which translates into a grade of B. The fund has returned 3.0% over the past year (grade of B), 4.5% over the past three years (grade of B) and 0.1% per year over the past five years (grade of B) and 2.0% per year over the past 10 years (grade of B).
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MRBKX Trailing NAV Total Returns Data as of 7/31/26
| Last Month |
Last Quarter |
Ann'l. 1Yr |
Ann'l. 3Yr |
Ann'l. 5Yr |
Ann'l. 10Yr |
|
| MRBKX Return (NAV) | -1.3% | -0.6% | 3.0% | 4.5% | 0.1% | 2.0% |
| MRBKX Grade | C | B | B | B | B | B |
| +/- Category | 0.0% | 0.1% | 0.2% | 0.3% | 0.3% | 0.2% |
| Intermediate Core-Plus Bond Avg | -1.3% | -0.7% | 2.7% | 4.2% | -0.2% | 1.8% |
| MRBKX Tax Cost Ratio | na | na | 1.7% | 1.8% | 1.6% | 1.4% |
MRBKX Annual NAV Total ReturnsData as of 7/31/26
| 2026 | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 | |
| MRBKX Return (NAV) | -0.3% | 7.3% | 2.6% | 7.4% | -13.8% | -0.7% | 8.9% | 10.1% | -0.9% | 4.3% | 3.9% |
| MRBKX Grade | B | C | B | A | C | C | B | B | C | C | C |
| +/- Category | 0.3% | -0.0% | 0.3% | 1.3% | -0.4% | -0.1% | 0.3% | 0.9% | -0.0% | -0.2% | -0.4% |
| Intermediate Core-Plus Bond Avg | -0.6% | 7.3% | 2.3% | 6.1% | -13.4% | -0.6% | 8.6% | 9.1% | -0.9% | 4.4% | 4.3% |
| Risk Measures | |
| Standard Deviation: | 5.7% |
| Total Risk Index: | 0.46 - Low |
| Category Risk Index: | 1.01 - Average |
| Category Risk Grade: | C (50% Rank) |
| Beta: | 1.00 |
| R-Squared: | 100% |
| Leveraged Fund: | No |
| Inverse Fund: | No |
| Portfolio Characteristics | |
| Equity Investment Style: | na |
| Bond Investment Style: | High Quality Moderate Sensitivity |
| Yield: | 4.3% |
| Dividend Distribution: | Monthly |
| Cap Gains Distribution: | Annually |
| Total Assets: | $8089 Mil |
| Fund Total Assets: | $3,988 Mil |
| Share Class Type: | Retirement |
| Portfolio Turnover: | 75% |
Management Team
| Number of Managers: 2 | |||
| Longest Tenure: 16.6 years | |||
| Average Tenure: 11.6 years | |||
| Managers (Year): Marston Joshua (2009), Mackey Alexander (2019) | |||
Portfolio Composition (as of 6/30/26)
| # of Holdings: | 1083 |
| % in Top 10 Holdings: | 25.2% |
| Fund is Non-Diversified: | No |
| % in Foreign Issues: | 11.6% |
Portfolio Allocation |
|
| Domestic Stock: | 0.0% |
| Foreign Stock: | 0.0% |
| Preferred Stock: | 1.2% |
| Domestic Bond: | 101.5% |
| Foreign Bond: | 11.6% |
| Convertible Bond: | 0.0% |
| Other: | 0.0% |
| Cash: | -14.2% |
Purchase Information
| Fund Family: | MFS |
| Phone Number: | 800-225-2606 |
| Website: | http://www.mfs.com |
| Status: | Open |
| Inception Date: | May 1, 2006 |
| Min. Initial Purchase: | $ 0 |
| Min. Initial IRA Purchase: | $ 0 |
| True No-Load: | Yes |
| Front Load Maximum: | 0.00% |
| Deferred Charge Maximum: | 0.00% |
| Redemption Charge Maximum: | 0.00% |
| 12b-1 Fee: | na |
Expenses and Fees | |
| Expense Ratio (%): | 0.36% ( Rating : Below Avg ) |
| Category Average Expense Ratio (%): | 0.78% |
| Share Class: | MFS Total Return Bond I |
| Min. Subsequent Purchase: | $ 0 |
| Min. Subsequent IRA Purchase: | $ 0 |
