BIOGEN INC

Ticker: BIIB CUSIP: 09062X103 Class: COM

Chesley Taft & Associates LLC's Holding History (CIK: 0001164632)

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

Q3 2019

Shares 3,749 Value ($000) $873 Avg Close $232.85 Range $215.78 - $246.99

Q2 2019

Shares 4,467 Value ($000) $1,045 Avg Close $230.90 Range $219.20 - $245.35

Q1 2019

Shares 4,542 Value ($000) $1,074 Avg Close $314.89 Range $216.12 - $344.00

Q4 2018

Shares 4,407 Value ($000) $1,326 Avg Close $319.14 Range $278.46 - $358.41

Q3 2018

Shares 4,237 Value ($000) $1,497 Avg Close $344.30 Range $288.13 - $388.67

Q2 2018

Shares 4,192 Value ($000) $1,217 Avg Close $281.15 Range $249.17 - $310.91

Q1 2018

Shares 4,482 Value ($000) $1,227 Avg Close $310.41 Range $259.76 - $370.57

Q4 2017

Shares 4,382 Value ($000) $1,396 Avg Close $320.80 Range $301.81 - $348.84

Q3 2017

Shares 4,257 Value ($000) $1,333 Avg Close $296.11 Range $269.50 - $330.00

Q2 2017

Shares 4,382 Value ($000) $1,189 Avg Close $264.42 Range $244.28 - $291.90

Q1 2017

Shares 4,257 Value ($000) $1,164 Avg Close $282.75 Range $260.50 - $301.42

Q4 2016

Shares 4,282 Value ($000) $1,214 Avg Close $296.43 Range $268.00 - $329.83

Q3 2016

Shares 6,412 Value ($000) $2,007 Avg Close $296.18 Range $240.07 - $333.65

Q2 2016

Shares 6,627 Value ($000) $1,603 Avg Close $263.54 Range $223.02 - $292.69

Q1 2016

Shares 6,562 Value ($000) $1,708 Avg Close $264.15 Range $242.07 - $301.02

Q4 2015

Shares 6,332 Value ($000) $1,940 Avg Close $287.35 Range $254.00 - $311.65

Q3 2015

Shares 6,692 Value ($000) $1,953 Avg Close $330.23 Range $265.00 - $412.24

Q2 2015

Shares 650 Value ($000) $263 Avg Close $401.33 Range $368.88 - $432.88

Q1 2015

Shares 650 Value ($000) $274 Avg Close $394.14 Range $334.40 - $480.18

Q4 2014

Shares 659 Value ($000) $224 Avg Close $323.51 Range $290.85 - $361.93

Q3 2014

Shares 659 Value ($000) $218 Avg Close $329.72 Range $298.31 - $349.00

Q2 2014

Shares 659 Value ($000) $208 Avg Close $300.97 Range $272.02 - $322.25

Period	Shares	Value ($000)	Average Close	Price Range
Q3 2019	3,749	$873	$232.85	$215.78 - $246.99
Q2 2019	4,467	$1,045	$230.90	$219.20 - $245.35
Q1 2019	4,542	$1,074	$314.89	$216.12 - $344.00
Q4 2018	4,407	$1,326	$319.14	$278.46 - $358.41
Q3 2018	4,237	$1,497	$344.30	$288.13 - $388.67
Q2 2018	4,192	$1,217	$281.15	$249.17 - $310.91
Q1 2018	4,482	$1,227	$310.41	$259.76 - $370.57
Q4 2017	4,382	$1,396	$320.80	$301.81 - $348.84
Q3 2017	4,257	$1,333	$296.11	$269.50 - $330.00
Q2 2017	4,382	$1,189	$264.42	$244.28 - $291.90
Q1 2017	4,257	$1,164	$282.75	$260.50 - $301.42
Q4 2016	4,282	$1,214	$296.43	$268.00 - $329.83
Q3 2016	6,412	$2,007	$296.18	$240.07 - $333.65
Q2 2016	6,627	$1,603	$263.54	$223.02 - $292.69
Q1 2016	6,562	$1,708	$264.15	$242.07 - $301.02
Q4 2015	6,332	$1,940	$287.35	$254.00 - $311.65
Q3 2015	6,692	$1,953	$330.23	$265.00 - $412.24
Q2 2015	650	$263	$401.33	$368.88 - $432.88
Q1 2015	650	$274	$394.14	$334.40 - $480.18
Q4 2014	659	$224	$323.51	$290.85 - $361.93
Q3 2014	659	$218	$329.72	$298.31 - $349.00
Q2 2014	659	$208	$300.97	$272.02 - $322.25