BIIB
Biogen Inc.Stock · HealthcareS&P 500 Equal Weight 0.2% · Nasdaq Composite 0.06% · S&P 500 0.05% · Russell 1000 0.05% · US Stock Market 0.04% · Russell 3000 0.04% · MSCI World 0.03% · MSCI ACWI 0.03%$217.10+0.78%
as of market close, Sep 11, 2026
☾ AH — —
Biogen Inc. monthly returns
Biogen Inc. has averaged 2.11% per month, positive in 53% of months. Month-by-month returns for Biogen Inc. (BIIB) below, through September 11, 2026 — the table lists the most recent months; the bar chart plots the last 5 years.
Average month
+2.1%
417 months
Best month
+83.8%
Jun 2000
Worst month
-40.5%
Feb 2005
Positive months
53%
of all months
Biogen Inc. monthly returns#
| Month | Path | Total return |
|---|---|---|
| Sep 2026 | +0.2% | |
| Aug 2026 | +6.8% | |
| Jul 2026 | -6.6% | |
| Jun 2026 | +10.9% | |
| May 2026 | +3.6% | |
| Apr 2026 | +3.2% | |
| Mar 2026 | -4.4% | |
| Feb 2026 | +6.6% | |
| Jan 2026 | +2.2% | |
| Dec 2025 | -3.4% | |
| Nov 2025 | +18.0% | |
| Oct 2025 | +10.1% | |
| Sep 2025 | +5.9% | |
| Aug 2025 | +3.3% | |
| Jul 2025 | +1.9% | |
| Jun 2025 | -3.2% | |
| May 2025 | +7.2% | |
| Apr 2025 | -11.5% | |
| Mar 2025 | -2.6% | |
| Feb 2025 | -2.4% | |
| Jan 2025 | -5.9% | |
| Dec 2024 | -4.8% | |
| Nov 2024 | -7.7% | |
| Oct 2024 | -10.2% | |
| Sep 2024 | -5.3% | |
| Aug 2024 | -4.0% | |
| Jul 2024 | -8.0% | |
| Jun 2024 | +3.1% | |
| May 2024 | +4.7% | |
| Apr 2024 | -0.4% | |
| Mar 2024 | -0.6% | |
| Feb 2024 | -12.0% | |
| Jan 2024 | -4.7% | |
| Dec 2023 | +10.5% | |
| Nov 2023 | -1.5% | |
| Oct 2023 | -7.6% | |
| Sep 2023 | -3.9% | |
| Aug 2023 | -1.0% | |
| Jul 2023 | -5.1% | |
| Jun 2023 | -3.9% | |
| May 2023 | -2.6% | |
| Apr 2023 | +9.4% | |
| Mar 2023 | +3.0% | |
| Feb 2023 | -7.2% | |
| Jan 2023 | +5.0% | |
| Dec 2022 | -9.3% | |
| Nov 2022 | +7.7% | |
| Oct 2022 | +6.2% | |
| Sep 2022 | +36.7% | |
| Aug 2022 | -9.2% | |
| Jul 2022 | +5.5% | |
| Jun 2022 | +2.0% | |
| May 2022 | -3.6% | |
| Apr 2022 | -1.5% | |
| Mar 2022 | -0.2% | |
| Feb 2022 | -6.6% | |
| Jan 2022 | -5.8% | |
| Dec 2021 | +1.8% | |
| Nov 2021 | -11.6% | |
| Oct 2021 | -5.8% | |
| Sep 2021 | -16.5% | |
| Aug 2021 | +3.7% | |
| Jul 2021 | -5.6% | |
| Jun 2021 | +29.5% | |
| May 2021 | +0.1% | |
| Apr 2021 | -4.4% | |
| Mar 2021 | +2.5% | |
| Feb 2021 | -3.4% | |
| Jan 2021 | +15.4% | |
| Dec 2020 | +2.0% | |
| Nov 2020 | -4.7% | |
| Oct 2020 | -11.1% | |
| Sep 2020 | -1.4% | |
| Aug 2020 | +4.7% | |
| Jul 2020 | +2.7% | |
| Jun 2020 | -12.9% | |
| May 2020 | +3.5% | |
| Apr 2020 | -6.2% | |
| Mar 2020 | +2.6% | |
| Feb 2020 | +14.7% | |
| Jan 2020 | -9.4% | |
| Dec 2019 | -1.0% | |
| Nov 2019 | +0.4% | |
| Oct 2019 | +28.3% | |
| Sep 2019 | +5.9% | |
| Aug 2019 | -7.6% | |
| Jul 2019 | +1.7% | |
| Jun 2019 | +6.6% | |
| May 2019 | -4.3% | |
| Apr 2019 | -3.0% | |
| Mar 2019 | -27.9% | |
| Feb 2019 | -1.7% | |
| Jan 2019 | +10.9% | |
| Dec 2018 | -9.8% | |
| Nov 2018 | +9.7% | |
| Oct 2018 | -13.9% | |
| Sep 2018 | -0.1% | |
| Aug 2018 | +5.7% | |
| Jul 2018 | +15.2% | |
| Jun 2018 | -1.3% | |
| May 2018 | +7.4% | |
| Apr 2018 | -0.1% | |
| Mar 2018 | -5.2% | |
| Feb 2018 | -16.9% | |
| Jan 2018 | +9.2% | |
| Dec 2017 | -1.1% | |
| Nov 2017 | +3.4% | |
| Oct 2017 | -0.5% | |
| Sep 2017 | -1.1% | |
| Aug 2017 | +9.3% | |
| Jul 2017 | +6.7% | |
| Jun 2017 | +9.5% | |
| May 2017 | -8.6% | |
| Apr 2017 | -0.8% | |
| Mar 2017 | -5.3% | |
| Feb 2017 | +4.1% | |
| Jan 2017 | -2.2% | |
| Dec 2016 | -3.6% | |
| Nov 2016 | +5.0% | |
| Oct 2016 | -10.5% |
Monthly total return (since Oct 2021)#
-30%-20%-10%0%10%20%30%
Oct 2021-5.8%
Nov 2021-12%
Dec 2021+1.8%
Jan 2022-5.8%2022
Feb 2022-6.6%
Mar 2022-0.19%
Apr 2022-1.5%
May 2022-3.6%
Jun 2022+2.0%
Jul 2022+5.5%
Aug 2022-9.2%
Sep 2022+37%
Oct 2022+6.2%
Nov 2022+7.7%
Dec 2022-9.3%
Jan 2023+5.0%2023
Feb 2023-7.2%
Mar 2023+3.0%
Apr 2023+9.4%
May 2023-2.6%
Jun 2023-3.9%
Jul 2023-5.1%
Aug 2023-1.0%
Sep 2023-3.9%
Oct 2023-7.6%
Nov 2023-1.5%
Dec 2023+11%
Jan 2024-4.7%2024
Feb 2024-12%
Mar 2024-0.63%
Apr 2024-0.38%
May 2024+4.7%
Jun 2024+3.1%
Jul 2024-8.0%
Aug 2024-4.0%
Sep 2024-5.3%
Oct 2024-10%
Nov 2024-7.7%
Dec 2024-4.8%
Jan 2025-5.9%2025
Feb 2025-2.4%
Mar 2025-2.6%
Apr 2025-12%
May 2025+7.2%
Jun 2025-3.2%
Jul 2025+1.9%
Aug 2025+3.3%
Sep 2025+5.9%
Oct 2025+10%
Nov 2025+18%
Dec 2025-3.4%
Jan 2026+2.2%2026
Feb 2026+6.6%
Mar 2026-4.4%
Apr 2026+3.2%
May 2026+3.6%
Jun 2026+11%
Jul 2026-6.6%
Aug 2026+6.8%
Sep 2026+0.21%
Methodology#
Monthly returns are total returns (dividends reinvested), computed from BIIB's split- and dividend-adjusted month-end closes. The table shows the most recent 120 months and the bar chart the most recent 60. See the year-by-year returns for the annual view. Past performance does not predict future returns; not investment advice.
FAQ#
- What is Biogen Inc.'s average monthly return?
- Biogen Inc. (BIIB) has averaged about 2.11% per month, positive in roughly 53% of months. The best month was Jun 2000 (+83.8%) and the worst was Feb 2005 (-40.5%).
More on Biogen Inc.
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