NASDAQ:BIIB | Historical Stock Price | BIOGEN INC.

Complete retained daily price history on its own workbook tab. Split-adjusted close keeps every historical share price on one comparable split basis. Cumulative dividend-reinvested close is the daily close of a rebased total-return index: it starts with one share at the earliest retained close, reinvests every distribution, and normalizes every forward and reverse split exactly once. Admitted exchange opening prices remain a distinct current-session series.

Available history
1991-09-17 to 2026-09-04
Data captured

Stock Price Chart

Blue: Split-adjusted close · Orange: Cumulative dividend-reinvested close

$0.34$1.42$6.01$25.38$107.26$453.211991-09-172026-08-27

Logarithmic scale. Both lines share the same starting value for the selected range.

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Historical Stock Price — 2005

DateSplit-adjusted closeCumulative dividend-reinvested closeReported volumeOpen priceExchange Volume
2005-12-30$45.28$45.282,610,800
2005-12-29$44.66$44.661,296,700
2005-12-28$45.18$45.182,052,300
2005-12-27$44.92$44.923,144,200
2005-12-23$45.52$45.521,402,000
2005-12-22$45.47$45.473,294,700
2005-12-21$44.39$44.392,799,100
2005-12-20$43.79$43.792,190,000
2005-12-19$44.09$44.093,322,100
2005-12-16$45.31$45.316,164,900
2005-12-15$45.11$45.112,351,700
2005-12-14$44.78$44.782,316,500
2005-12-13$45.12$45.122,957,900
2005-12-12$44.76$44.762,001,100
2005-12-09$44.67$44.672,962,600
2005-12-08$44.93$44.936,767,800
2005-12-07$42.78$42.783,142,300
2005-12-06$42.36$42.362,386,400
2005-12-05$42.75$42.752,242,900
2005-12-02$43.45$43.452,188,000
2005-12-01$43.42$43.422,696,400
2005-11-30$42.81$42.812,273,000
2005-11-29$43.03$43.032,365,200
2005-11-28$43.42$43.423,332,600
2005-11-25$44.49$44.49904,400
2005-11-23$44.83$44.831,892,200
2005-11-22$44.76$44.764,167,900
2005-11-21$45.12$45.122,746,400
2005-11-18$45.33$45.335,642,400
2005-11-17$44.81$44.812,737,200
2005-11-16$43.72$43.722,122,600
2005-11-15$43.81$43.812,479,300
2005-11-14$43.74$43.743,242,200
2005-11-11$44.91$44.913,737,800
2005-11-10$43.98$43.983,801,000
2005-11-09$42.63$42.632,260,200
2005-11-08$42.92$42.923,019,300
2005-11-07$41.84$41.842,276,000
2005-11-04$41.98$41.982,456,100
2005-11-03$41.39$41.392,799,700
2005-11-02$41.16$41.162,635,500
2005-11-01$40.29$40.292,704,700
2005-10-31$40.63$40.636,250,000
2005-10-28$38.49$38.493,852,200
2005-10-27$38.35$38.354,947,000
2005-10-26$40.01$40.013,178,300
2005-10-25$40.42$40.422,786,100
2005-10-24$39.65$39.652,519,100
2005-10-21$39.09$39.093,788,900
2005-10-20$39.01$39.014,226,700
2005-10-19$39.27$39.273,460,100
2005-10-18$38.65$38.652,953,300
2005-10-17$38.63$38.633,570,700
2005-10-14$38.02$38.023,183,300
2005-10-13$37.06$37.064,343,100
2005-10-12$35.94$35.943,198,400
2005-10-11$36.57$36.573,433,900
2005-10-10$37.52$37.522,494,200
2005-10-07$37.71$37.712,644,500
2005-10-06$37.24$37.245,141,900
2005-10-05$38.86$38.862,903,100
2005-10-04$40.26$40.263,723,700
2005-10-03$39.92$39.924,007,800
2005-09-30$39.48$39.483,192,400
2005-09-29$38.60$38.603,017,600
2005-09-28$38.15$38.153,392,400
2005-09-27$38.05$38.053,915,200
2005-09-26$38.46$38.463,752,300
2005-09-23$38.56$38.562,756,800
2005-09-22$38.91$38.913,290,700
2005-09-21$39.42$39.424,064,500
2005-09-20$40.23$40.233,389,700
2005-09-19$40.29$40.292,190,300
2005-09-16$41.24$41.243,983,700
2005-09-15$40.44$40.442,058,900
2005-09-14$40.67$40.671,807,200
2005-09-13$41.30$41.302,348,600
2005-09-12$41.88$41.882,207,800
2005-09-09$41.86$41.867,677,700
2005-09-08$42.44$42.442,055,500
2005-09-07$42.47$42.473,160,100
2005-09-06$42.41$42.413,548,300
2005-09-02$42.42$42.421,915,100
2005-09-01$42.80$42.804,856,700
2005-08-31$42.14$42.144,596,300
2005-08-30$40.90$40.902,086,400
2005-08-29$40.99$40.993,031,600
2005-08-26$41.05$41.053,481,600
2005-08-25$40.92$40.923,553,500
2005-08-24$39.87$39.872,367,400
2005-08-23$39.85$39.852,757,400
2005-08-22$40.17$40.172,007,600
2005-08-19$40.24$40.242,792,600
2005-08-18$40.60$40.602,275,600
2005-08-17$40.55$40.553,241,500
2005-08-16$41.08$41.082,686,200
2005-08-15$41.71$41.712,978,300
2005-08-12$41.58$41.583,810,700
2005-08-11$41.73$41.732,814,900
2005-08-10$41.27$41.275,231,900
2005-08-09$41.24$41.2419,210,100
2005-08-08$38.42$38.423,657,200
2005-08-05$38.12$38.125,060,900
2005-08-04$39.48$39.484,632,000
2005-08-03$40.69$40.692,268,600
2005-08-02$40.84$40.842,849,400
2005-08-01$40.42$40.425,343,000
2005-07-29$39.29$39.292,973,700
2005-07-28$39.90$39.904,739,600
2005-07-27$39.48$39.488,833,800
2005-07-26$38.82$38.825,011,800
2005-07-25$38.50$38.503,270,500
2005-07-22$38.46$38.464,907,600
2005-07-21$38.86$38.863,691,000
2005-07-20$39.26$39.265,891,500
2005-07-19$38.24$38.242,714,800
2005-07-18$38.10$38.102,638,200
2005-07-15$37.82$37.824,306,800
2005-07-14$37.76$37.764,400,600
2005-07-13$36.38$36.383,293,000
2005-07-12$36.34$36.342,869,700
2005-07-11$36.32$36.324,109,900
2005-07-08$35.43$35.434,036,300
2005-07-07$34.76$34.763,429,900
2005-07-06$34.65$34.653,801,500
2005-07-05$34.09$34.092,643,800
2005-07-01$34.08$34.081,760,900
2005-06-30$34.45$34.452,821,800
2005-06-29$34.88$34.884,457,600
2005-06-28$34.36$34.362,341,400
2005-06-27$33.99$33.993,680,900
2005-06-24$34.08$34.084,458,700
2005-06-23$34.19$34.195,197,600
2005-06-22$34.89$34.893,618,200
2005-06-21$35.25$35.252,983,900
2005-06-20$35.40$35.403,097,100
2005-06-17$35.94$35.946,990,400
2005-06-16$36.25$36.256,178,600
2005-06-15$35.03$35.033,581,100
2005-06-14$34.76$34.764,559,500
2005-06-13$34.79$34.793,725,100
2005-06-10$35.01$35.013,893,400
2005-06-09$35.13$35.1315,943,300
2005-06-08$33.35$33.3513,943,500
2005-06-07$35.07$35.074,019,200
2005-06-06$35.37$35.376,866,200
2005-06-03$36.40$36.408,073,500
2005-06-02$38.07$38.0710,907,000
2005-06-01$39.77$39.773,736,800
2005-05-31$39.10$39.103,111,100
2005-05-27$39.64$39.642,095,100
2005-05-26$39.34$39.346,989,200
2005-05-25$37.99$37.992,505,000
2005-05-24$38.35$38.353,029,100
2005-05-23$39.11$39.112,924,900
2005-05-20$39.06$39.065,207,800
2005-05-19$39.95$39.953,038,900
2005-05-18$39.26$39.263,282,300
2005-05-17$38.65$38.653,284,800
2005-05-16$38.55$38.552,058,000
2005-05-13$38.90$38.904,713,000
2005-05-12$39.34$39.345,158,000
2005-05-11$38.77$38.774,276,700
2005-05-10$38.91$38.914,346,900
2005-05-09$38.70$38.703,017,700
2005-05-06$38.45$38.452,676,900
2005-05-05$38.52$38.523,192,600
2005-05-04$38.72$38.724,824,400
2005-05-03$37.72$37.725,795,500
2005-05-02$37.32$37.325,046,200
2005-04-29$36.24$36.243,379,000
2005-04-28$35.98$35.986,779,100
2005-04-27$35.84$35.843,435,000
2005-04-26$36.21$36.214,502,800
2005-04-25$35.35$35.352,606,100
2005-04-22$35.38$35.383,298,400
2005-04-21$35.42$35.422,551,500
2005-04-20$34.80$34.803,663,400
2005-04-19$35.47$35.473,567,500
2005-04-18$35.73$35.733,020,400
2005-04-15$35.79$35.795,536,900
2005-04-14$36.04$36.043,318,400
2005-04-13$36.45$36.456,032,100
2005-04-12$36.70$36.704,615,900
2005-04-11$35.75$35.754,449,600
2005-04-08$36.08$36.083,274,900
2005-04-07$36.53$36.536,917,400
2005-04-06$35.40$35.407,834,300
2005-04-05$34.77$34.774,192,800
2005-04-04$34.61$34.615,240,400
2005-04-01$34.74$34.7412,616,900
2005-03-31$34.51$34.5141,007,700
2005-03-30$38.35$38.353,176,500
2005-03-29$37.69$37.695,021,000
2005-03-28$38.10$38.103,313,800
2005-03-24$38.80$38.804,583,600
2005-03-23$38.10$38.103,632,000
2005-03-22$38.10$38.107,335,100
2005-03-21$38.27$38.273,706,700
2005-03-18$38.26$38.265,837,800
2005-03-17$38.16$38.1610,854,300
2005-03-16$37.19$37.1929,867,000
2005-03-15$38.07$38.077,257,100
2005-03-14$39.41$39.416,374,200
2005-03-11$38.03$38.035,524,200
2005-03-10$38.61$38.6110,669,400
2005-03-09$39.31$39.3112,759,100
2005-03-08$38.35$38.3514,022,400
2005-03-07$37.59$37.5910,636,100
2005-03-04$37.53$37.5324,063,700
2005-03-03$39.33$39.3321,420,400
2005-03-02$40.88$40.8824,290,800
2005-03-01$41.26$41.2652,507,900
2005-02-28$38.65$38.65117,940,000
2005-02-25$67.28$67.281,977,500
2005-02-24$66.68$66.683,896,200
2005-02-23$65.58$65.581,702,400
2005-02-22$65.34$65.343,047,400
2005-02-18$66.97$66.972,611,000
2005-02-17$67.57$67.577,394,900
2005-02-16$67.29$67.291,869,500
2005-02-15$67.04$67.042,800,000
2005-02-14$66.99$66.991,833,700
2005-02-11$66.70$66.702,947,600
2005-02-10$65.92$65.922,518,500
2005-02-09$65.03$65.033,369,100
2005-02-08$66.23$66.234,683,800
2005-02-07$66.15$66.153,391,400
2005-02-04$66.95$66.953,565,200
2005-02-03$65.18$65.181,992,200
2005-02-02$65.50$65.502,931,900
2005-02-01$64.72$64.722,307,800
2005-01-31$64.96$64.964,170,300
2005-01-28$62.20$62.204,686,900
2005-01-27$63.69$63.693,854,200
2005-01-26$63.47$63.473,666,300
2005-01-25$63.08$63.083,215,000
2005-01-24$63.00$63.004,911,600
2005-01-21$64.83$64.835,277,800
2005-01-20$64.83$64.836,126,000
2005-01-19$66.93$66.932,905,000
2005-01-18$67.80$67.803,872,100
2005-01-14$66.58$66.583,151,300
2005-01-13$64.87$64.873,595,600
2005-01-12$67.11$67.113,410,200
2005-01-11$65.80$65.802,902,400
2005-01-10$66.82$66.824,390,300
2005-01-07$66.09$66.093,257,100
2005-01-06$65.19$65.192,963,900
2005-01-05$64.84$64.843,587,400
2005-01-04$64.76$64.763,888,500
2005-01-03$66.29$66.293,506,500