MFRBX Performance — MFS Research Fund, Class B
Data updated: 2026-08-25
MFRBX returned +5.79% year to date and +13.37% over one year to Jun 2026. Annualised returns are +14.67% over 3 years and +8.62% over 5 years. The fund trailed its US Large Blend category average: $100 invested three years ago grew to $151, against $157 for the category, and to $113 over one year, against $118. Volatility over the past three years was 12.67% a year. In the 12 months to Jun 2026 the fund lost a net $99.2M, and assets reached $7.88B.
MFRBX Growth of $100
What $100 invested in MFS Research Fund grew to, compounded from monthly returns reported on SEC Form N-PORT, against the US Large Blend category average over the same months.
| Period | MFRBX | Category average |
|---|---|---|
| 1 year (Jul 2025 – Jun 2026) | $113 | $118 |
| 3 years (Jul 2023 – Jun 2026) | $151 | $157 |
| 5 years (Jul 2021 – Jun 2026) | $151 | $161 |
| Since data start (Jul 2019 – Jun 2026) | $218 | $229 |
MFRBX Trailing Returns
Total returns to Jun 2026, from SEC N-PORT.
| Period | Total return |
|---|---|
| YTD | +5.79% |
| 1 year | +13.37% |
| 3 years (annualised) | +14.67% |
| 5 years (annualised) | +8.62% |
MFRBX Annual Returns
Calendar-year total returns of MFS Research Fund, compounded from monthly SEC N-PORT returns. Partial years show the months covered.
| Year | Total return |
|---|---|
| 2026 (Jan–Jun) | +5.79% |
| 2025 | +11.99% |
| 2024 | +17.91% |
| 2023 | +21.56% |
| 2022 | −17.89% |
| 2021 | +23.77% |
| 2020 | +15.75% |
| 2019 (Jul–Dec) | +9.18% |
MFRBX 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 | +1.4% | −1.4% | −5.1% | +8.7% | +2.9% | −0.4% | — | — | — | — | — | — |
| 2025 | +3.6% | −2.5% | −6.2% | −1.0% | +6.2% | +4.8% | +2.5% | +1.2% | +1.8% | +1.7% | +0.1% | −0.3% |
| 2024 | +1.2% | +5.5% | +3.0% | −4.9% | +4.0% | +2.5% | +1.0% | +1.5% | +1.6% | −0.7% | +5.5% | −3.2% |
| 2023 | +5.7% | −3.9% | +2.5% | +1.9% | +0.1% | +5.9% | +3.0% | −1.8% | −5.0% | −1.3% | +9.0% | +4.4% |
| 2022 | −5.6% | −3.3% | +2.2% | −8.0% | +1.0% | −7.5% | +8.6% | −4.0% | −8.4% | +7.4% | +5.2% | −5.0% |
| 2021 | −2.1% | +3.0% | +4.2% | +6.0% | +0.5% | +2.0% | +2.7% | +2.6% | −5.1% | +6.2% | −2.2% | +4.4% |
| 2020 | +1.0% | −7.8% | −12.5% | +12.0% | +5.1% | +1.1% | +5.0% | +6.5% | −3.4% | −2.9% | +10.0% | +3.5% |
| 2019 | — | — | — | — | — | — | +2.1% | −1.1% | +0.7% | +0.8% | +3.6% | +2.9% |
MFRBX Risk
Risk measures from monthly returns over Jul 2023 – Jun 2026.
- 3-year volatility (annualised): 12.67%
- 3-year Sharpe ratio: 0.80 (vs 4.5% risk-free rate)
- Best month: +9.00% (Nov 2023)
- Worst month: −6.18% (Mar 2025)
MFRBX Fund Flows
Monthly money in and out of MFS Research Fund, from SEC Form N-PORT.
- 12-month net flow: −$99.2M
- 12-month gross sales (incl. reinvestments): $1.7B
- Sales ÷ redemptions: 0.95×
| Month | Sales | Redemptions | Net flow |
|---|---|---|---|
| Jun 2026 | $41.4M | $114.0M | −$72.6M |
| May 2026 | $37.8M | $152.6M | −$114.8M |
| Apr 2026 | $45.7M | $155.1M | −$109.4M |
| Mar 2026 | $53.3M | $145.2M | −$92.0M |
| Feb 2026 | $61.3M | $232.5M | −$171.2M |
| Jan 2026 | $63.6M | $118.2M | −$54.7M |
| Dec 2025 | $1.2B | $219.4M | $966.0M |
| Nov 2025 | $46.7M | $142.1M | −$95.4M |
| Oct 2025 | $54.9M | $128.5M | −$73.6M |
| Sep 2025 | $43.0M | $108.7M | −$65.7M |
| Aug 2025 | $41.1M | $109.9M | −$68.8M |
| Jul 2025 | $41.0M | $187.9M | −$146.9M |
MFRBX Assets Under Management
Net assets of MFS Research Fund by report date, from SEC N-PORT filings.
| Report date | Net assets |
|---|---|
| 2026-06-30 | $7.88B |
| 2026-03-31 | $7.33B |
| 2025-12-31 | $8.02B |
| 2025-09-30 | $8.20B |
| 2025-06-30 | $8.02B |
| 2025-03-31 | $7.44B |
| 2024-12-31 | $8.02B |
| 2024-09-30 | $8.27B |
| 2024-06-30 | $7.99B |
| 2024-03-31 | $8.02B |
| 2023-12-31 | $7.57B |
| 2023-09-30 | $7.03B |
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.