MFS Corporate Bond Fund
Actively managed U.S. bond fund
As of its 2026 Q2 report, MFS Corporate Bond Fund held 432 positions with $4.38B in net assets. Its ten largest holdings made up 7.5% of the fund. The MFBFX share class costs 0.76% a year. Over the 12 months to May 2026, MFBFX returned 5.9%, with dividends reinvested. In 2026 Q3 it added 49 new positions and exited 51.
The funds investment objective is to seek total return with an emphasis on current income, but also considering capital appreciation.
The fund invests at least 80% of assets in corporate debt instruments selected through bottom-up fundamental analysis, with the majority in investment-grade quality but up to a significant portion in below-investment-grade debt; it may also hold U.S. Government securities and foreign securities across sectors. Because the fund may invest meaningfully in below-investment-grade debt instruments, credit risk is material to returns.
What you own
| Company | Weight | Value | Shares |
|---|---|---|---|
MFS Institutional Money Market Portfolio | 1.76% | $77.33M | — |
UBS Group AG 3.13% floating · due 2030-08-13 | 0.77% | $33.88M | — |
JPMorgan Chase & Co. 2.54% floating · due 2032-11-08 | 0.76% | $33.15M | — |
Boeing Co. (The) 5.80% · due 2050-05-01 | 0.74% | $32.61M | — |
Charles Schwab Corp. (The) 4.91% floating · due 2036-11-14 | 0.62% | $27.03M | — |
Bermuda 5.00% · due 2032-07-15 | 0.59% | $25.69M | — |
Morgan Stanley 5.07% floating · due 2037-01-30 | 0.58% | $25.28M | — |
Sumitomo Mitsui Financial Group, Inc. 1.71% · due 2031-01-12 | 0.57% | $25.14M | — |
UBS Group AG 5.58% floating · due 2036-05-09 | 0.54% | $23.70M | — |
CaixaBank SA 6.84% floating · due 2034-09-13 | 0.54% | $23.47M | — |
The 200 largest of 432 holdings, with the share counts as filed, open with a free account.
What the fund is made of
Percentages are of fund net assets. Rounding, liabilities and short positions can make totals differ from 100%.
| Bonds | 94.47% |
| Securitized | 3.19% |
| Cash & short-term | 1.76% |
| Derivatives | -0.17% |
The outer band is exposure held short — written against the portfolio rather than part of it, which is why it sits outside the ring and why the two are never netted into one figure.
Derivatives are shown at market value, not notional exposure.
By sector
- Other
- 25.3%
- International
- 22.0%
- Financials
- 15.0%
- Utilities
- 5.6%
- 12 other sectors
- 32.1%
- Other
- 25.3%
- International
- 22.0%
- Financials
- 15.0%
- Utilities
- 5.6%
- Industrials
- 5.5%
- Health Care
- 4.4%
- Information Technology
- 3.9%
- Government
- 3.2%
- Real Estate
- 3.1%
- Securitized
- 3.0%
- Consumer Discretionary
- 2.0%
- Cash
- 1.9%
- Energy
- 1.9%
- Communication Services
- 1.5%
- Consumer Staples
- 1.2%
- Materials
- 0.4%
How it has done
MFBFX share class · total returns with dividends reinvested
Volatility over the last 12 months: 3.36%. Past returns are a record, not a forecast.
Jun 2026 and Jul 2026 have been filed since the trailing figures were struck, so they are not in the table above or the curve — every figure here shares one cut-off, which is what makes them comparable with other funds.
The 9 share classes hold the same portfolio
| Share class | Expense ratio | 1 year | 3 years | 5 years | Worst fall |
|---|---|---|---|---|---|
| 0.76% | +5.87% | +17.17% | +2.61% | -5.44% | |
| 0.51% | +6.30% | +18.14% | +4.00% | -5.28% | |
| 1.51% | +5.19% | +14.60% | -1.14% | -5.54% | |
| 1.51% | +5.08% | +14.61% | -1.21% | -5.54% | |
| 0.51% | +6.21% | +18.05% | +3.91% | -5.29% | |
| 1.51% | +5.19% | +14.69% | -1.11% | -5.54% | |
| 1.01% | +5.70% | +16.31% | +1.36% | -5.41% | |
| 0.76% | +5.96% | +17.17% | +2.70% | -5.34% | |
| 0.42% | +6.31% | +18.37% | +4.39% | -5.28% |
These classes hold the same portfolio, so the 5.60pp spread over 5 years is the cost difference between them — roughly 1.12pp a year — not a difference in what they own.
Fees & fund details
MFS Corporate Bond Fund is an actively managed U.S. bond fund.
- Asset class
- Bonds
- Region
- United States
- Management
- Actively managed
- Fund type
- Open-end fund
- Credit quality
- Investment grade
- Rate sensitivity
- Intermediate duration
- Expense ratio, by class
- 0.42% – 1.51%· MFBFX 0.76%
- Portfolio turnover
- 38.00% a year · as of 2025 Q3
Net is what a holder pays after the adviser's contractual waiver; gross is before it. A waiver can expire.
Turnover is how much of the portfolio was replaced in a year.
Classified from what the fund holds, not from its name · 2026 Q2. The summary is a paraphrase of the prospectus; the objective is verbatim.
What changed this quarter
Positions that entered or left the fund since its previous filing. Positions that were only resized are not listed.
49 new· the largest 8
51 exited· the largest 8
Debt profile
What this fund holds — value-weighted across its bond and securitized long positions · as of 2026-04-30
Share of the fund's debt by how its coupon behaves — the fact that decides whether a rate move reaches this portfolio at all.
| Fixed rate | 78.9% |
| Floating rate | 21.1% |
Share of the fund's debt value in each maturity band, shortest first.
| <1y | 1.6% |
| 1-3y | 11.2% |
| 3-5y | 17.8% |
| 5-10y | 40.1% |
| 10y+ | 29.3% |
These three overlap — one holding can be in arrears and paying in kind at once — so they are shown separately and never summed.
Risk profile
Interest-rate and credit-spread sensitivity, both in years · as of 2026Q2
Most of this fund’s sensitivity is to interest rates, with credit spreads carrying nearly as much.
Where the loss would come from. The two shocks are the same size, so this is the balance of the fund's two sensitivities rather than a bet on one moving more.
| Interest rates | 52% |
| Credit spreads | 48% |
Filers report the impact of a 0.01% move only, so the total is our own scaling of that one number and overstates the loss on most bonds — read it as approximate, never as precise. The two sensitivities overlap rather than add up: they measure the same positions against different shocks, which is why the durations above are shown side by side and never summed.
Share of the fund's spread duration carried by each credit tier.
| Investment grade | +5.70 yr |
| High yield | +0.37 yr |
Share of duration at each point, shortest first. A positive figure loses value when spreads widen; a negative one offsets — a credit hedge.
| 3 mo | 0.02 yr | 0% |
| 1 yr | 0.53 yr | 8% |
| 5 yr | 1.95 yr | 29% |
| 10 yr | 2.67 yr | 40% |
| 30 yr | 1.52 yr | 23% |
| 3 mo | 0.02 yr | 0% |
| 1 yr | 0.49 yr | 8% |
| 5 yr | 1.91 yr | 31% |
| 10 yr | 2.46 yr | 41% |
| 30 yr | 1.18 yr | 19% |
The two bands measure the same positions against different shocks and do not add — a Treasury carries rate duration and no spread duration, a floating-rate credit the reverse. Rate tenors are also summed across every currency the fund discloses.
Show the numbers
| Tenor | Rate yrs | IG yrs | HY yrs | IG $/bp | HY $/bp |
|---|---|---|---|---|---|
| 3 mo | +0.02 | +0.02 | +0.00 | $8.1k | $1.4k |
| 1 yr | +0.53 | +0.41 | +0.08 | $178.8k | $37.0k |
| 5 yr | +1.95 | +1.73 | +0.17 | $760.4k | $76.3k |
| 10 yr | +2.67 | +2.38 | +0.08 | $1.04m | $34.8k |
| 30 yr | +1.52 | +1.15 | +0.03 | $505.6k | $11.7k |
Dollar change per 1bp of spread movement, as filed and sign-anchored. A blank cell was not filed; a zero was.
Duration contribution in years, summing to the fund's 6.68 yr.
This is where the fund's rate exposure sits, not its currency risk — most international bond funds hedge the currency back to dollars, and the size of those hedges is not in the filing. Tenors are also summed across curves, so a 5-year JPY point and a 5-year USD point are added together.
A newer credit-spread reading (2026Q3) is on file. This page holds one quarter across every figure on it, so that one appears here next quarter.
Understand how this fund fits with the rest.
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