BIOGEN INC

Ticker: BIIB CUSIP: 09062X103 Class: COM

CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM's Holding History (CIK: 0001081019)

Note: Option positions (PUT/CALL) are excluded.

Q4 2025

Shares 226,380 Value ($000) $39,841 Avg Close $163.37 Range $138.00 - $185.17

Q3 2025

Shares 234,818 Value ($000) $32,893 Avg Close $135.17 Range $121.05 - $150.28

Q2 2025

Shares 238,691 Value ($000) $29,977 Avg Close $124.60 Range $110.04 - $137.32

Q1 2025

Shares 230,535 Value ($000) $31,546 Avg Close $142.96 Range $128.51 - $157.09

Q4 2024

Shares 233,318 Value ($000) $35,679 Avg Close $168.67 Range $145.07 - $195.00

Q3 2024

Shares 230,507 Value ($000) $44,681 Avg Close $209.21 Range $188.78 - $238.00

Q2 2024

Shares 230,935 Value ($000) $53,535 Avg Close $217.32 Range $189.44 - $237.54

Q1 2024

Shares 227,072 Value ($000) $48,964 Avg Close $234.20 Range $211.02 - $268.30

Q4 2023

Shares 226,422 Value ($000) $58,591 Avg Close $245.62 Range $220.86 - $269.43

Q3 2023

Shares 226,333 Value ($000) $58,170 Avg Close $267.47 Range $251.85 - $287.60

Q2 2023

Shares 233,553 Value ($000) $66,528 Avg Close $297.86 Range $273.39 - $319.76

Q1 2023

Shares 247,784 Value ($000) $68,891 Avg Close $276.70 Range $254.80 - $295.90

Q4 2022

Shares 251,522 Value ($000) $69,651 Avg Close $282.44 Range $250.31 - $311.88

Q3 2022

Shares 250,138 Value ($000) $66,787 Avg Close $212.38 Range $193.65 - $283.44

Q2 2022

Shares 252,062 Value ($000) $51,406 Avg Close $204.43 Range $187.16 - $225.50

Q1 2022

Shares 256,743 Value ($000) $54,070 Avg Close $217.46 Range $192.67 - $249.00

Q4 2021

Shares 273,845 Value ($000) $65,701 Avg Close $257.12 Range $221.72 - $290.76

Q3 2021

Shares 266,379 Value ($000) $75,383 Avg Close $327.75 Range $282.64 - $372.12

Q2 2021

Shares 264,242 Value ($000) $91,499 Avg Close $302.94 Range $257.03 - $468.55

Q1 2021

Shares 295,017 Value ($000) $82,531 Avg Close $269.69 Range $238.40 - $296.38

Q4 2020

Shares 296,506 Value ($000) $72,602 Avg Close $259.08 Range $223.25 - $363.92

Q3 2020

Shares 335,843 Value ($000) $95,272 Avg Close $278.91 Range $261.87 - $312.00

Q2 2020

Shares 356,309 Value ($000) $95,330 Avg Close $300.59 Range $257.60 - $350.24

Q1 2020

Shares 375,795 Value ($000) $118,894 Avg Close $303.47 Range $262.25 - $374.99

Q4 2019

Shares 390,149 Value ($000) $115,769 Avg Close $277.46 Range $219.70 - $318.00

Q3 2019

Shares 338,467 Value ($000) $78,802 Avg Close $232.85 Range $215.78 - $246.99

Q2 2019

Shares 350,910 Value ($000) $82,067 Avg Close $230.90 Range $219.20 - $245.35

Q1 2019

Shares 349,898 Value ($000) $82,709 Avg Close $314.89 Range $216.12 - $344.00

Q4 2018

Shares 347,510 Value ($000) $104,573 Avg Close $319.14 Range $278.46 - $358.41

Q3 2018

Shares 326,168 Value ($000) $115,238 Avg Close $344.30 Range $288.13 - $388.67

Q2 2018

Shares 340,970 Value ($000) $98,963 Avg Close $281.15 Range $249.17 - $310.91

Q1 2018

Shares 341,268 Value ($000) $93,446 Avg Close $310.41 Range $259.76 - $370.57

Q4 2017

Shares 352,819 Value ($000) $112,398 Avg Close $320.80 Range $301.81 - $348.84

Q3 2017

Shares 358,060 Value ($000) $112,116 Avg Close $296.11 Range $269.50 - $330.00

Q2 2017

Shares 392,134 Value ($000) $106,410 Avg Close $264.42 Range $244.28 - $291.90

Q1 2017

Shares 435,961 Value ($000) $119,200 Avg Close $282.75 Range $260.50 - $301.42

Q4 2016

Shares 455,961 Value ($000) $129,301 Avg Close $296.43 Range $268.00 - $329.83

Q3 2016

Shares 468,161 Value ($000) $146,548 Avg Close $296.18 Range $240.07 - $333.65

Q2 2016

Shares 464,261 Value ($000) $112,268 Avg Close $263.54 Range $223.02 - $292.69

Q1 2016

Shares 473,577 Value ($000) $123,282 Avg Close $264.15 Range $242.07 - $301.02

Q4 2015

Shares 413,067 Value ($000) $126,543 Avg Close $287.35 Range $254.00 - $311.65

Q3 2015

Shares 428,917 Value ($000) $125,162 Avg Close $330.23 Range $265.00 - $412.24

Q2 2015

Shares 429,617 Value ($000) $173,539 Avg Close $401.33 Range $368.88 - $432.88

Q1 2015

Shares 434,607 Value ($000) $183,508 Avg Close $394.14 Range $334.40 - $480.18

Q4 2014

Shares 442,107 Value ($000) $150,073 Avg Close $323.51 Range $290.85 - $361.93

Q3 2014

Shares 437,935 Value ($000) $144,873 Avg Close $329.72 Range $298.31 - $349.00

Q2 2014

Shares 433,449 Value ($000) $136,671 Avg Close $300.97 Range $272.02 - $322.25

Q1 2014

Shares 431,849 Value ($000) $132,090 Avg Close $317.43 Range $270.62 - $358.89

Q4 2013

Shares 429,749 Value ($000) $120,222 Avg Close $258.65 Range $221.07 - $298.82

Q3 2013

Shares 426,849 Value ($000) $102,768 Avg Close $223.81 Range $203.55 - $248.95

Q2 2013

Shares 413,644 Value ($000) $89,016 Avg Close $213.68 Range $191.80 - $242.64

Q1 2013

Shares 416,464 Value ($000) $80,340 Avg Close $161.63 Range $139.72 - $192.92

Period	Shares	Value ($000)	Average Close	Price Range
Q4 2025	226,380	$39,841	$163.37	$138.00 - $185.17
Q3 2025	234,818	$32,893	$135.17	$121.05 - $150.28
Q2 2025	238,691	$29,977	$124.60	$110.04 - $137.32
Q1 2025	230,535	$31,546	$142.96	$128.51 - $157.09
Q4 2024	233,318	$35,679	$168.67	$145.07 - $195.00
Q3 2024	230,507	$44,681	$209.21	$188.78 - $238.00
Q2 2024	230,935	$53,535	$217.32	$189.44 - $237.54
Q1 2024	227,072	$48,964	$234.20	$211.02 - $268.30
Q4 2023	226,422	$58,591	$245.62	$220.86 - $269.43
Q3 2023	226,333	$58,170	$267.47	$251.85 - $287.60
Q2 2023	233,553	$66,528	$297.86	$273.39 - $319.76
Q1 2023	247,784	$68,891	$276.70	$254.80 - $295.90
Q4 2022	251,522	$69,651	$282.44	$250.31 - $311.88
Q3 2022	250,138	$66,787	$212.38	$193.65 - $283.44
Q2 2022	252,062	$51,406	$204.43	$187.16 - $225.50
Q1 2022	256,743	$54,070	$217.46	$192.67 - $249.00
Q4 2021	273,845	$65,701	$257.12	$221.72 - $290.76
Q3 2021	266,379	$75,383	$327.75	$282.64 - $372.12
Q2 2021	264,242	$91,499	$302.94	$257.03 - $468.55
Q1 2021	295,017	$82,531	$269.69	$238.40 - $296.38
Q4 2020	296,506	$72,602	$259.08	$223.25 - $363.92
Q3 2020	335,843	$95,272	$278.91	$261.87 - $312.00
Q2 2020	356,309	$95,330	$300.59	$257.60 - $350.24
Q1 2020	375,795	$118,894	$303.47	$262.25 - $374.99
Q4 2019	390,149	$115,769	$277.46	$219.70 - $318.00
Q3 2019	338,467	$78,802	$232.85	$215.78 - $246.99
Q2 2019	350,910	$82,067	$230.90	$219.20 - $245.35
Q1 2019	349,898	$82,709	$314.89	$216.12 - $344.00
Q4 2018	347,510	$104,573	$319.14	$278.46 - $358.41
Q3 2018	326,168	$115,238	$344.30	$288.13 - $388.67
Q2 2018	340,970	$98,963	$281.15	$249.17 - $310.91
Q1 2018	341,268	$93,446	$310.41	$259.76 - $370.57
Q4 2017	352,819	$112,398	$320.80	$301.81 - $348.84
Q3 2017	358,060	$112,116	$296.11	$269.50 - $330.00
Q2 2017	392,134	$106,410	$264.42	$244.28 - $291.90
Q1 2017	435,961	$119,200	$282.75	$260.50 - $301.42
Q4 2016	455,961	$129,301	$296.43	$268.00 - $329.83
Q3 2016	468,161	$146,548	$296.18	$240.07 - $333.65
Q2 2016	464,261	$112,268	$263.54	$223.02 - $292.69
Q1 2016	473,577	$123,282	$264.15	$242.07 - $301.02
Q4 2015	413,067	$126,543	$287.35	$254.00 - $311.65
Q3 2015	428,917	$125,162	$330.23	$265.00 - $412.24
Q2 2015	429,617	$173,539	$401.33	$368.88 - $432.88
Q1 2015	434,607	$183,508	$394.14	$334.40 - $480.18
Q4 2014	442,107	$150,073	$323.51	$290.85 - $361.93
Q3 2014	437,935	$144,873	$329.72	$298.31 - $349.00
Q2 2014	433,449	$136,671	$300.97	$272.02 - $322.25
Q1 2014	431,849	$132,090	$317.43	$270.62 - $358.89
Q4 2013	429,749	$120,222	$258.65	$221.07 - $298.82
Q3 2013	426,849	$102,768	$223.81	$203.55 - $248.95
Q2 2013	413,644	$89,016	$213.68	$191.80 - $242.64
Q1 2013	416,464	$80,340	$161.63	$139.72 - $192.92