William Blair & Company’s Biogen BIIB Stock Holding History
Bought
Maintained
Sold
| Quarter | Market Value | Status | Shares |
Change in Stake | Trade Value | Portfolio Weight | Portfolio Position | |
|---|---|---|---|---|---|---|---|---|
|
2026
Q1 | $2.36M | Buy |
12,854
+4,411
| +52% | +$813K | 0.01% | 685 |
|
|
2025
Q4 | $1.49M | Sell |
8,443
-5,577
| -40% | -$911K | ﹤0.01% | 826 |
|
|
2025
Q3 | $1.96M | Sell |
14,020
-824
| -6% | -$111K | 0.01% | 735 |
|
|
2025
Q2 | $1.86M | Buy |
14,844
+1,561
| +12% | +$195K | 0.01% | 731 |
|
|
2025
Q1 | $1.82M | Buy |
13,283
+234
| +2% | +$33.5K | 0.01% | 736 |
|
|
2024
Q4 | $2M | Buy |
13,049
+894
| +7% | +$151K | 0.01% | 715 |
|
|
2024
Q3 | $2.36M | Sell |
12,155
-939
| -7% | -$196K | 0.01% | 661 |
|
|
2024
Q2 | $3.04M | Buy |
13,094
+227
| +2% | +$49.3K | 0.01% | 592 |
|
|
2024
Q1 | $2.77M | Buy |
12,867
+1,132
| +10% | +$265K | 0.01% | 606 |
|
|
2023
Q4 | $3.04M | Sell |
11,735
-2,388
| -17% | -$587K | 0.01% | 573 |
|
|
2023
Q3 | $3.63M | Buy |
14,123
+3,568
| +34% | +$954K | 0.01% | 511 |
|
|
2023
Q2 | $3.01M | Sell |
10,555
-357
| -3% | -$106K | 0.01% | 569 |
|
|
2023
Q1 | $3.03M | Buy |
10,912
+580
| +6% | +$160K | 0.01% | 556 |
|
|
2022
Q4 | $2.86M | Sell |
10,332
-2,156
| -17% | -$609K | 0.01% | 548 |
|
|
2022
Q3 | $3.33M | Sell |
12,488
-1,526
| -11% | -$324K | 0.02% | 507 |
|
|
2022
Q2 | $2.86M | Sell |
14,014
-512
| -4% | -$105K | 0.01% | 545 |
|
|
2022
Q1 | $3.06M | Sell |
14,526
-3,236
| -18% | -$704K | 0.01% | 589 |
|
|
2021
Q4 | $4.26M | Buy |
17,762
+4,077
| +30% | +$1.05M | 0.01% | 511 |
|
|
2021
Q3 | $3.87M | Buy |
13,685
+2,297
| +20% | +$753K | 0.01% | 513 |
|
|
2021
Q2 | $3.94M | Buy |
11,388
+1,072
| +10% | +$325K | 0.01% | 517 |
|
|
2021
Q1 | $2.89M | Buy |
10,316
+344
| +3% | +$92.8K | 0.01% | 583 |
|
|
2020
Q4 | $2.44M | Sell |
9,972
-412
| -4% | -$106K | 0.01% | 597 |
|
|
2020
Q3 | $2.95M | Buy |
10,384
+1,038
| +11% | +$290K | 0.01% | 501 |
|
|
2020
Q2 | $2.5M | Sell |
9,346
-56
| -0.6% | -$16.8K | 0.01% | 508 |
|
|
2020
Q1 | $2.98M | Sell |
9,402
-2,489
| -21% | -$755K | 0.02% | 442 |
|
|
2019
Q4 | $3.53M | Buy |
+11,891
| New | +$3.3M | 0.02% | 477 |
|
|
2019
Q3 | – | Sell |
-10,244
| Closed | – | – | 1698 |
|
|
2019
Q2 | $0 | Sell |
10,244
-4,974
| -33% | -$1.15M | ﹤0.01% | 1732 |
|
|
2019
Q1 | $3.6M | Sell |
15,218
-1,437
| -9% | -$452K | 0.02% | 427 |
|
|
2018
Q4 | $5.01M | Sell |
16,655
-1,794
| -10% | -$573K | 0.04% | 333 |
|
|
2018
Q3 | $6.52M | Buy |
18,449
+2,735
| +17% | +$942K | 0.04% | 324 |
|
|
2018
Q2 | $4.56M | Sell |
15,714
-8,323
| -35% | -$2.34M | 0.03% | 372 |
|
|
2018
Q1 | $6.58M | Sell |
24,037
-1,062
| -4% | -$330K | 0.05% | 298 |
|
|
2017
Q4 | $8M | Buy |
25,099
+1,046
| +4% | +$336K | 0.05% | 269 |
|
|
2017
Q3 | $7.53M | Buy |
24,053
+9,340
| +63% | +$2.77M | 0.06% | 268 |
|
|
2017
Q2 | $3.99M | Sell |
14,713
-1,185
| -7% | -$313K | 0.03% | 397 |
|
|
2017
Q1 | $4.5M | Sell |
15,898
-8,225
| -34% | -$2.33M | 0.04% | 341 |
|
|
2016
Q4 | $6.84M | Buy |
24,123
+383
| +2% | +$114K | 0.06% | 258 |
|
|
2016
Q3 | $7.43M | Buy |
23,740
+198
| +0.8% | +$58.6K | 0.07% | 247 |
|
|
2016
Q2 | $5.69M | Sell |
23,542
-15,530
| -40% | -$4.09M | 0.05% | 275 |
|
|
2016
Q1 | $10.2M | Buy |
39,072
+1,577
| +4% | +$417K | 0.1% | 196 |
|
|
2015
Q4 | $11.5M | Sell |
37,495
-45,638
| -55% | -$13.1M | 0.11% | 195 |
|
|
2015
Q3 | $24.3M | Buy |
83,133
+49,636
| +148% | +$16.4M | 0.21% | 124 |
|
|
2015
Q2 | $13.5M | Buy |
33,497
+7,519
| +29% | +$3.02M | 0.02% | 789 |
|
|
2015
Q1 | $11M | Buy |
25,978
+8,849
| +52% | +$3.49M | 0.02% | 825 |
|
|
2014
Q4 | $5.81M | Buy |
17,129
+6,912
| +68% | +$2.24M | 0.01% | 1011 |
|
|
2014
Q3 | $3.38M | Buy |
10,217
+867
| +9% | +$286K | 0.01% | 1110 |
|
|
2014
Q2 | $2.95M | Sell |
9,350
-25,223
| -73% | -$7.59M | ﹤0.01% | 1133 |
|
|
2014
Q1 | $10.6M | Buy |
34,573
+2,974
| +9% | +$944K | 0.02% | 809 |
|
|
2013
Q4 | $8.84M | Buy |
31,599
+10,891
| +53% | +$2.82M | 0.01% | 815 |
|
|
2013
Q3 | $4.99M | Buy |
20,708
+367
| +2% | +$82.1K | 0.01% | 898 |
|
|
2013
Q2 | $4.38M | Buy |
+20,341
| New | +$4.35M | 0.01% | 903 |
|
Other funds holding BIIB
VCM
VPM
William Blair & Company's BIIB Position: Q1 2026 in Review
William Blair & Company increased its Biogen (BIIB) stake by 52% in Q1 2026, buying an estimated $813K and bringing the position to 12,854 shares worth $2.36M. The position accounts for 0.01% of the portfolio, ranked #685.
William Blair & Company first reported a position in BIIB in Q2 2013 and has held it in 51 quarters since. The position peaked at $24.3M in Q3 2015. 1,004 funds tracked by Wall St. Rank hold BIIB as of Q1 2026.
- William Blair & Company held 12,854 shares of Biogen worth $2.36M as of Q1 2026.
- William Blair & Company bought 4,411 Biogen shares in Q1 2026, an estimated $813K.
- Biogen made up 0.01% of William Blair & Company's portfolio in Q1 2026, its #685 holding.
- William Blair & Company first reported a position in Biogen in Q2 2013 and has held it in 51 quarters since.
- William Blair & Company's Biogen position peaked at $24.3M in Q3 2015.
- 1,004 funds tracked by Wall St. Rank held Biogen as of Q1 2026.
Based on William Blair & Company's 13F filing for Q1 2026, filed 8 May 2026.