Observatory · observe first
Biogen
BIIB · United States · Biotechnology · matched S&P 500 member. Follow its market-weight contribution.
Historical time machine
Latest available · not live
20182026
Universe weight
0.056%
12M weight contribution
+0.015 pp
3M weight contribution
+0.001 pp
12M price return
+61.3%
Share of matched S&P 500 members
Monthly observations through Sep 2026
Company price index
A separate dimension from market allocation
Historical observations
Most recent 24 observations at or before the selected month
| Month | Market cap | Universe weight | 12M weight change | 12M return | Above 6M weight average |
|---|---|---|---|---|---|
| Sep 2026 | $33.3bn | 0.056% | +0.015 pp | +61.3% | Yes |
| Aug 2026 | $32.0bn | 0.053% | +0.013 pp | +63.9% | Yes |
| Jul 2026 | $30.0bn | 0.052% | +0.013 pp | +58.6% | Yes |
| Jun 2026 | $31.9bn | 0.055% | +0.016 pp | +72.0% | Yes |
| May 2026 | $28.9bn | 0.050% | +0.007 pp | +51.0% | Yes |
| Apr 2026 | $27.9bn | 0.038% | -0.005 pp | +56.3% | No |
| Mar 2026 | $26.9bn | 0.039% | -0.008 pp | +34.0% | No |
| Feb 2026 | $28.2bn | 0.039% | -0.007 pp | +36.5% | No |
| Jan 2026 | $26.4bn | 0.050% | +0.004 pp | +25.0% | Yes |
| Dec 2025 | $25.8bn | 0.051% | +0.000 pp | +15.1% | Yes |
| Nov 2025 | $26.7bn | 0.052% | +0.001 pp | +13.4% | Yes |
| Oct 2025 | $22.6bn | 0.044% | -0.015 pp | -11.3% | Yes |
| Sep 2025 | $20.5bn | 0.041% | -0.025 pp | -27.7% | Yes |
| Aug 2025 | $19.4bn | 0.040% | -0.032 pp | -35.4% | No |
| Jul 2025 | $18.8bn | 0.040% | -0.016 pp | -40.0% | No |
| Jun 2025 | $18.4bn | 0.040% | -0.024 pp | -45.8% | No |
| May 2025 | $19.0bn | 0.043% | -0.020 pp | -42.3% | No |
| Apr 2025 | $17.7bn | 0.043% | -0.048 pp | -43.6% | No |
| Mar 2025 | $20.0bn | 0.048% | -0.039 pp | -36.5% | No |
| Feb 2025 | $20.6bn | 0.046% | -0.044 pp | -35.3% | No |
| Jan 2025 | $21.0bn | 0.047% | -0.060 pp | -41.6% | No |
| Dec 2024 | $22.3bn | 0.051% | -0.061 pp | -40.9% | No |
| Nov 2024 | $23.4bn | 0.052% | -0.054 pp | -31.4% | No |
| Oct 2024 | $25.4bn | 0.060% | -0.057 pp | -26.7% | No |
Its weight is estimated market cap divided by the total estimated market cap of matched S&P 500 members for the month. This is not an official float-adjusted S&P index weight.