MMIDX Performance — MFS Municipal Income Fund, Class A1
Data updated: 2026-08-25
MMIDX returned +2.87% year to date and +7.72% over one year to Jun 2026. Annualised returns are +4.67% over 3 years and +1.14% over 5 years. The fund beat its Long-Term Municipal Bond category average: $100 invested three years ago grew to $115, against $112 for the category, and to $108 over one year, against $108. Volatility over the past three years was 6.34% a year. In the 12 months to Jun 2026 the fund took in a net $1.1B, and assets reached $7.18B.
MMIDX Growth of $100
What $100 invested in MFS Municipal 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 | MMIDX | Category average |
|---|---|---|
| 1 year (Jul 2025 – Jun 2026) | $108 | $108 |
| 3 years (Jul 2023 – Jun 2026) | $115 | $112 |
| 5 years (Jul 2021 – Jun 2026) | $106 | $103 |
| Since data start (Jul 2019 – Jun 2026) | $116 | $113 |
MMIDX Trailing Returns
Total returns to Jun 2026, from SEC N-PORT.
| Period | Total return |
|---|---|
| YTD | +2.87% |
| 1 year | +7.72% |
| 3 years (annualised) | +4.67% |
| 5 years (annualised) | +1.14% |
MMIDX Annual Returns
Calendar-year total returns of MFS Municipal Income Fund, compounded from monthly SEC N-PORT returns. Partial years show the months covered.
| Year | Total return |
|---|---|
| 2026 (Jan–Jun) | +2.87% |
| 2025 | +3.60% |
| 2024 | +3.55% |
| 2023 | +7.00% |
| 2022 | −10.83% |
| 2021 | +3.25% |
| 2020 | +4.42% |
| 2019 (Jul–Dec) | +2.50% |
MMIDX 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% | +1.5% | −2.1% | +1.2% | +0.6% | +1.1% | — | — | — | — | — | — |
| 2025 | +0.3% | +1.1% | −1.7% | −0.9% | −0.7% | +0.8% | −0.8% | +0.9% | +3.1% | +1.2% | +0.3% | 0.0% |
| 2024 | +0.1% | +0.1% | +0.3% | −1.3% | +0.3% | +2.0% | +1.1% | +0.8% | +1.4% | −1.5% | +1.8% | −1.5% |
| 2023 | +3.3% | −2.4% | +1.9% | +0.2% | −0.8% | +0.9% | +0.3% | −1.3% | −3.2% | −1.8% | +7.3% | +2.9% |
| 2022 | −2.7% | −0.6% | −3.3% | −3.1% | +1.2% | −2.1% | +2.7% | −2.5% | −4.3% | −1.1% | +5.0% | −0.1% |
| 2021 | +1.2% | −1.5% | +0.7% | +1.1% | +0.7% | +0.6% | +0.9% | −0.3% | −0.9% | −0.2% | +1.0% | +0.2% |
| 2020 | +2.1% | +1.6% | −6.3% | −2.4% | +3.0% | +2.0% | +1.9% | −0.2% | 0.0% | −0.3% | +2.0% | +1.2% |
| 2019 | — | — | — | — | — | — | +0.6% | +2.1% | −0.7% | 0.0% | +0.2% | +0.3% |
MMIDX Risk
Risk measures from monthly returns over Jul 2023 – Jun 2026.
- 3-year volatility (annualised): 6.34%
- 3-year Sharpe ratio: 0.03 (vs 4.5% risk-free rate)
- Best month: +7.26% (Nov 2023)
- Worst month: −3.22% (Sep 2023)
MMIDX Fund Flows
Monthly money in and out of MFS Municipal Income Fund, from SEC Form N-PORT.
- 12-month net flow: $1.1B
- 12-month gross sales (incl. reinvestments): $2.7B
- Sales ÷ redemptions: 1.69×
| Month | Sales | Redemptions | Net flow |
|---|---|---|---|
| Jun 2026 | $150.0M | $109.3M | $40.7M |
| May 2026 | $158.0M | $120.2M | $37.8M |
| Apr 2026 | $145.5M | $125.2M | $20.4M |
| Mar 2026 | $158.5M | $135.0M | $23.5M |
| Feb 2026 | $161.8M | $98.0M | $63.8M |
| Jan 2026 | $440.7M | $150.8M | $289.9M |
| Dec 2025 | $201.8M | $179.3M | $22.6M |
| Nov 2025 | $150.4M | $105.8M | $44.6M |
| Oct 2025 | $525.7M | $138.5M | $387.1M |
| Sep 2025 | $209.0M | $120.3M | $88.7M |
| Aug 2025 | $202.7M | $164.1M | $38.6M |
| Jul 2025 | $221.3M | $164.2M | $57.0M |
MMIDX Assets Under Management
Net assets of MFS Municipal Income Fund by report date, from SEC N-PORT filings.
| Report date | Net assets |
|---|---|
| 2026-06-30 | $7.18B |
| 2026-03-31 | $6.95B |
| 2025-12-31 | $6.65B |
| 2025-09-30 | $6.16B |
| 2025-06-30 | $5.85B |
| 2025-03-31 | $5.89B |
| 2024-12-31 | $5.95B |
| 2024-09-30 | $5.60B |
| 2024-06-30 | $5.23B |
| 2024-03-31 | $5.14B |
| 2023-12-31 | $5.02B |
| 2023-09-30 | $4.68B |
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.