MMIIX Performance — MFS Municipal High Income Fund, Class I
Data updated: 2026-09-28
MMIIX returned +1.75% year to date and +7.71% over one year to Jul 2026. Annualised returns are +5.18% over 3 years and +0.55% over 5 years. The fund beat its Long-Term Municipal Bond category average: $100 invested three years ago grew to $116, against $110 for the category, and to $108 over one year, against $106. Volatility over the past three years was 6.73% a year. In the 12 months to Jul 2026 the fund took in a net $573.5M, and assets reached $5.57B.
MMIIX Growth of $100
What $100 invested in MFS Municipal High Income Fund grew to, compounded from monthly returns reported on SEC Form N-PORT, against the Long-Term Municipal Bond category average over the same months.
| Period | MMIIX | Category average |
|---|---|---|
| 1 year (Aug 2025 – Jul 2026) | $108 | $106 |
| 3 years (Aug 2023 – Jul 2026) | $116 | $110 |
| 5 years (Aug 2021 – Jul 2026) | $103 | $101 |
| Since data start (Aug 2019 – Jul 2026) | $115 | $110 |
MMIIX Trailing Returns
Total returns to Jul 2026, from SEC N-PORT.
| Period | Total return |
|---|---|
| YTD | +1.75% |
| 1 year | +7.71% |
| 3 years (annualised) | +5.18% |
| 5 years (annualised) | +0.55% |
MMIIX Annual Returns
Calendar-year total returns of MFS Municipal High Income Fund, compounded from monthly SEC N-PORT returns. Partial years show the months covered.
| Year | Total return |
|---|---|
| 2026 (Jan–Jul) | +1.75% |
| 2025 | +3.50% |
| 2024 | +7.08% |
| 2023 | +6.27% |
| 2022 | −13.88% |
| 2021 | +5.17% |
| 2020 | +3.50% |
| 2019 (Aug–Dec) | +2.34% |
MMIIX Monthly Returns
Monthly total returns as reported on SEC Form N-PORT.
| Year | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2026 | +0.6% | +1.6% | −1.9% | +1.3% | +0.8% | +1.3% | −1.9% | — | — | — | — | — |
| 2025 | +0.5% | +1.3% | −1.9% | −1.1% | −0.6% | +0.6% | −1.0% | +0.7% | +3.3% | +1.3% | +0.4% | +0.1% |
| 2024 | +0.5% | +0.4% | +0.8% | −1.3% | +0.6% | +3.1% | +1.3% | +1.0% | +1.8% | −1.3% | +1.5% | −1.5% |
| 2023 | +3.9% | −2.8% | +1.5% | +0.3% | −0.6% | +0.4% | +0.4% | −1.3% | −3.6% | −2.0% | +7.0% | +3.3% |
| 2022 | −2.8% | −0.8% | −3.6% | −3.2% | +1.1% | −3.3% | +3.2% | −2.5% | −5.8% | −1.8% | +5.6% | −0.5% |
| 2021 | +1.8% | −1.2% | +0.6% | +1.2% | +1.0% | +1.1% | +1.1% | −0.3% | −1.0% | −0.3% | +1.2% | +0.1% |
| 2020 | +2.1% | +1.8% | −8.8% | −3.4% | +2.9% | +3.2% | +2.3% | +0.1% | +0.1% | −0.1% | +2.2% | +1.7% |
| 2019 | — | — | — | — | — | — | — | +2.2% | −0.5% | −0.1% | +0.3% | +0.4% |
MMIIX Risk
Risk measures from monthly returns over Aug 2023 – Jul 2026.
- 3-year volatility (annualised): 6.73%
- 3-year Sharpe ratio: 0.10 (vs 4.5% risk-free rate)
- Best month: +7.00% (Nov 2023)
- Worst month: −3.57% (Sep 2023)
MMIIX Fund Flows
Monthly money in and out of MFS Municipal High Income Fund, from SEC Form N-PORT.
- 12-month net flow: $573.5M
- 12-month gross sales (incl. reinvestments): $1.9B
- Sales ÷ redemptions: 1.42×
| Month | Sales | Redemptions | Net flow |
|---|---|---|---|
| Jul 2026 | $116.0M | $99.5M | $16.5M |
| Jun 2026 | $115.1M | $91.6M | $23.4M |
| May 2026 | $258.7M | $86.7M | $172.0M |
| Apr 2026 | $120.2M | $101.9M | $18.3M |
| Mar 2026 | $108.8M | $104.9M | $3.9M |
| Feb 2026 | $154.5M | $79.9M | $74.6M |
| Jan 2026 | $138.9M | $98.7M | $40.1M |
| Dec 2025 | $174.7M | $151.0M | $23.8M |
| Nov 2025 | $241.5M | $101.1M | $140.4M |
| Oct 2025 | $175.8M | $143.5M | $32.2M |
| Sep 2025 | $152.9M | $132.0M | $20.9M |
| Aug 2025 | $169.9M | $162.4M | $7.5M |
MMIIX Assets Under Management
Net assets of MFS Municipal High Income Fund by report date, from SEC N-PORT filings.
| Report date | Net assets |
|---|---|
| 2026-07-31 | $5.57B |
| 2026-04-30 | $5.40B |
| 2026-01-31 | $5.32B |
| 2025-10-31 | $5.11B |
| 2025-07-31 | $4.84B |
| 2025-04-30 | $4.82B |
| 2025-01-31 | $4.73B |
| 2024-10-31 | $4.54B |
| 2024-07-31 | $4.39B |
| 2024-04-30 | $4.16B |
| 2024-01-31 | $4.29B |
| 2023-10-31 | $3.92B |
For information only. Not investment advice: figures are as reported in SEC filings and may contain errors or be out of date. Past performance does not guarantee future results.