$1,000 in Biogen Inc. in 2021 → $950 today
If you'd invested $1,000 in Biogen Inc. (BIIB) on January 1, 2021, buying at the December 2020 month-end close of $245, and held to the latest close on 2026-10-16, you'd have $950. That's a -5.0% price return. Through September 2026, the latest month the fund has reported, the same $1,000 became $923 in BIIB and $2,208 in an S&P 500 index fund (TSP C Fund). The fund figure includes reinvested dividends; the stock figure does not, so the comparison favors the fund.
Nearby years: 2019 · 2020 · 2022 · 2023 · 2024 · 2025 all years →
FAQ
How much is $1,000 invested in BIIB in 2021 worth today?
$950 at the latest close (2026-10-16), a price return of -5.0%.
Did $1,000 in BIIB in 2021 beat the market?
No. From the December 2020 month-end through September 2026, BIIB trailed an S&P 500 index fund by 58.2%: the fund (the TSP C Fund, dividends included) turned the same $1,000 into $2,208, and BIIB (price only) turned it into $923.
What does "month-end close" mean for this calculation?
It is a month's last price on IEX: the last regular-session trade on the month's final trading day. Here the buy is the December 2020 close, the price entering 2021, and the position is valued at the latest close (2026-10-16).
Is the 2021–2026 return in BIIB typical?
No single year is typical. BIIB's best calendar year since 2019 was 2026 (year to date), at +32.3%, and its worst was 2024, at -40.9%.
Methodology
The figures use BIIB's price data from January 2021 through 2026-10-16.
The entry price is the December 2020 month-end close and the exit is the latest close, both from IEX Historical Data. Price return: adjusted for stock splits, dividends not included. The market comparison uses the TSP C Fund's monthly returns, published at tsp.gov.
Buying at a month-end close misses the highs and lows inside the month, and the figures ignore taxes and fees. To try another amount, month or monthly contribution, use the BIIB calculator, which also shows the best and worst entry points in your window.
Compute your own BIIB scenario
Prices as of the last IEX trade on 2026-10-16. Data delayed end-of-day.