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 — 1999

DateSplit-adjusted closeCumulative dividend-reinvested closeReported volumeOpen priceExchange Volume
1999-12-31$32.75$32.751,224,300
1999-12-30$31.32$31.322,124,900
1999-12-29$31.92$31.921,825,800
1999-12-28$32.50$32.501,639,200
1999-12-27$32.63$32.633,137,400
1999-12-23$31.77$31.778,518,800
1999-12-22$28.69$28.695,734,800
1999-12-21$24.06$24.064,609,800
1999-12-20$21.08$21.082,865,600
1999-12-17$20.33$20.333,681,000
1999-12-16$19.75$19.751,884,000
1999-12-15$20.42$20.423,277,200
1999-12-14$19.70$19.703,455,400
1999-12-13$21.15$21.152,409,600
1999-12-10$19.81$19.816,177,600
1999-12-09$18.92$18.924,954,200
1999-12-08$19.79$19.796,821,400
1999-12-07$18.92$18.926,771,600
1999-12-06$18.92$18.928,268,000
1999-12-03$21.14$21.149,977,400
1999-12-02$20.86$20.862,257,800
1999-12-01$20.65$20.654,876,200
1999-11-30$21.13$21.132,455,800
1999-11-29$22.30$22.301,383,000
1999-11-26$23.17$23.17703,800
1999-11-24$22.56$22.561,092,600
1999-11-23$22.05$22.053,304,800
1999-11-22$22.42$22.423,871,800
1999-11-19$20.83$20.832,500,800
1999-11-18$20.83$20.839,226,200
1999-11-17$21.31$21.315,192,400
1999-11-16$20.51$20.512,289,600
1999-11-15$19.23$19.232,409,000
1999-11-12$19.77$19.771,899,600
1999-11-11$20.24$20.242,619,600
1999-11-10$20.67$20.672,040,600
1999-11-09$21.63$21.631,273,800
1999-11-08$21.67$21.672,587,800
1999-11-05$21.10$21.104,474,800
1999-11-04$20.94$20.944,620,600
1999-11-03$19.90$19.905,053,200
1999-11-02$19.34$19.343,383,400
1999-11-01$20.25$20.252,328,600
1999-10-29$19.36$19.364,069,800
1999-10-28$18.89$18.894,345,200
1999-10-27$18.29$18.291,662,000
1999-10-26$18.46$18.461,821,000
1999-10-25$18.89$18.892,150,400
1999-10-22$18.35$18.356,022,800
1999-10-21$19.25$19.258,970,600
1999-10-20$17.38$17.384,845,000
1999-10-19$16.32$16.326,118,800
1999-10-18$14.82$14.826,231,600
1999-10-15$15.51$15.514,335,600
1999-10-14$16.63$16.633,229,800
1999-10-13$17.16$17.162,540,400
1999-10-12$18.04$18.041,915,200
1999-10-11$18.17$18.175,355,600
1999-10-08$17.42$17.426,020,400
1999-10-07$17.60$17.603,565,200
1999-10-06$17.83$17.832,993,400
1999-10-05$16.32$16.324,805,400
1999-10-04$15.76$15.762,108,400
1999-10-01$15.71$15.711,303,800
1999-09-30$15.67$15.675,350,800
1999-09-29$16.36$16.363,579,000
1999-09-28$15.74$15.743,818,400
1999-09-27$15.81$15.816,297,000
1999-09-24$15.61$15.615,012,400
1999-09-23$16.26$16.2612,201,000
1999-09-22$18.04$18.042,065,200
1999-09-21$17.35$17.353,624,600
1999-09-20$17.80$17.803,178,800
1999-09-17$17.93$17.934,257,000
1999-09-16$17.55$17.558,383,800
1999-09-15$18.21$18.217,119,000
1999-09-14$18.34$18.347,909,800
1999-09-13$19.94$19.9415,994,200
1999-09-10$17.57$17.5724,073,800
1999-09-09$20.63$20.6330,854,400
1999-09-08$22.78$22.782,389,200
1999-09-07$22.52$22.521,525,200
1999-09-03$22.08$22.081,272,000
1999-09-02$21.08$21.081,585,200
1999-09-01$21.58$21.581,057,200
1999-08-31$21.18$21.182,072,400
1999-08-30$21.29$21.292,899,200
1999-08-27$21.71$21.711,606,200
1999-08-26$21.63$21.631,710,600
1999-08-25$22.00$22.005,147,400
1999-08-24$22.59$22.596,796,200
1999-08-23$22.85$22.853,738,000
1999-08-20$21.00$21.002,112,600
1999-08-19$20.54$20.541,903,200
1999-08-18$19.99$19.992,332,800
1999-08-17$19.50$19.502,250,000
1999-08-16$20.58$20.582,232,600
1999-08-13$20.79$20.793,706,200
1999-08-12$19.57$19.573,767,400
1999-08-11$20.06$20.064,858,200
1999-08-10$19.44$19.448,450,400
1999-08-09$18.65$18.656,754,200
1999-08-06$17.21$17.211,005,000
1999-08-05$16.92$16.921,662,600
1999-08-04$16.58$16.582,036,400
1999-08-03$16.64$16.642,137,200
1999-08-02$16.67$16.672,356,800
1999-07-30$16.52$16.521,914,600
1999-07-29$16.57$16.572,247,000
1999-07-28$16.66$16.664,020,600
1999-07-27$16.33$16.332,635,800
1999-07-26$15.08$15.083,646,200
1999-07-23$14.71$14.713,658,800
1999-07-22$13.92$13.922,589,000
1999-07-21$13.90$13.906,254,400
1999-07-20$13.73$13.733,434,400
1999-07-19$14.32$14.323,943,800
1999-07-16$16.03$16.032,598,600
1999-07-15$15.49$15.491,943,400
1999-07-14$14.55$14.553,306,000
1999-07-13$13.92$13.922,326,800
1999-07-12$13.75$13.754,567,200
1999-07-09$14.02$14.021,972,200
1999-07-08$13.75$13.752,236,200
1999-07-07$13.86$13.863,846,000
1999-07-06$13.78$13.785,797,800
1999-07-02$13.02$13.021,146,600
1999-07-01$12.75$12.751,524,000
1999-06-30$12.84$12.844,782,600
1999-06-29$12.58$12.583,740,400
1999-06-28$11.66$11.661,477,200
1999-06-25$11.18$11.182,361,000
1999-06-24$11.10$11.101,441,800
1999-06-23$11.09$11.091,508,400
1999-06-22$11.42$11.422,013,000
1999-06-21$11.49$11.492,142,000
1999-06-18$11.19$11.191,781,400
1999-06-17$10.85$10.852,262,600
1999-06-16$10.59$10.594,371,600
1999-06-15$9.75$9.751,070,400
1999-06-14$9.65$9.65751,800
1999-06-11$9.69$9.691,914,600
1999-06-10$9.38$9.381,353,600
1999-06-09$9.76$9.761,275,000
1999-06-08$9.83$9.832,580,000
1999-06-07$9.86$9.862,402,400
1999-06-04$9.21$9.211,735,800
1999-06-03$9.19$9.191,261,200
1999-06-02$9.03$9.033,500,400
1999-06-01$9.67$9.676,237,000
1999-05-28$8.41$8.413,943,200
1999-05-27$8.42$8.421,996,200
1999-05-26$8.49$8.491,553,400
1999-05-25$8.58$8.58942,600
1999-05-24$8.69$8.691,404,000
1999-05-21$9.17$9.171,039,200
1999-05-20$9.17$9.171,755,000
1999-05-19$9.05$9.051,102,800
1999-05-18$9.04$9.041,997,400
1999-05-17$9.46$9.461,510,800
1999-05-14$9.92$9.922,692,800
1999-05-13$10.03$10.032,891,400
1999-05-12$9.58$9.58774,600
1999-05-11$9.50$9.501,341,600
1999-05-10$9.52$9.521,629,600
1999-05-07$9.83$9.831,562,400
1999-05-06$9.44$9.441,380,000
1999-05-05$9.44$9.442,153,400
1999-05-04$9.36$9.363,114,600
1999-05-03$9.17$9.172,854,200
1999-04-30$8.46$8.461,602,600
1999-04-29$8.69$8.691,622,400
1999-04-28$8.73$8.731,331,400
1999-04-27$9.21$9.211,077,600
1999-04-26$8.75$8.751,384,800
1999-04-23$8.79$8.791,375,200
1999-04-22$8.82$8.821,642,200
1999-04-21$9.51$9.513,808,800
1999-04-20$9.08$9.087,174,200
1999-04-19$7.13$7.133,063,600
1999-04-16$8.19$8.193,077,400
1999-04-15$8.31$8.311,849,800
1999-04-14$8.75$8.751,615,200
1999-04-13$9.44$9.441,669,200
1999-04-12$9.58$9.585,971,800
1999-04-09$9.58$9.583,282,000
1999-04-08$8.98$8.981,888,800
1999-04-07$8.80$8.802,594,400
1999-04-06$9.23$9.231,599,600
1999-04-05$9.19$9.194,359,000
1999-04-01$8.77$8.771,679,400
1999-03-31$8.56$8.562,635,800
1999-03-30$8.43$8.431,149,000
1999-03-29$8.56$8.561,722,000
1999-03-26$8.67$8.671,193,400
1999-03-25$8.63$8.632,365,800
1999-03-24$8.17$8.171,495,200
1999-03-23$8.02$8.02890,400
1999-03-22$7.98$7.98795,000
1999-03-19$7.83$7.833,368,400
1999-03-18$8.17$8.173,918,600
1999-03-17$8.33$8.332,884,800
1999-03-16$8.31$8.313,584,400
1999-03-15$8.25$8.251,854,000
1999-03-12$8.70$8.703,045,000
1999-03-11$9.17$9.172,427,000
1999-03-10$9.15$9.155,107,200
1999-03-09$9.08$9.083,280,200
1999-03-08$8.75$8.755,737,800
1999-03-05$8.58$8.582,389,800
1999-03-04$8.35$8.353,885,000
1999-03-03$8.04$8.047,197,000
1999-03-02$7.67$7.671,920,600
1999-03-01$7.40$7.401,014,600
1999-02-26$7.22$7.221,869,000
1999-02-25$7.52$7.521,350,600
1999-02-24$7.54$7.54817,800
1999-02-23$7.66$7.661,221,600
1999-02-22$7.65$7.652,712,000
1999-02-19$7.54$7.543,957,000
1999-02-18$7.16$7.162,165,400
1999-02-17$6.88$6.883,075,600
1999-02-16$6.96$6.961,569,600
1999-02-12$6.85$6.851,447,800
1999-02-11$7.17$7.172,318,400
1999-02-10$6.99$6.997,157,400
1999-02-09$7.21$7.214,250,400
1999-02-08$7.35$7.353,313,800
1999-02-05$7.11$7.111,718,400
1999-02-04$7.52$7.522,550,600
1999-02-03$7.83$7.833,216,600
1999-02-02$8.31$8.311,214,400
1999-02-01$8.50$8.502,074,800
1999-01-29$8.42$8.422,473,800
1999-01-28$7.83$7.831,920,600
1999-01-27$7.60$7.602,386,200
1999-01-26$7.94$7.942,729,400
1999-01-25$7.77$7.772,476,800
1999-01-22$8.02$8.024,309,800
1999-01-21$7.89$7.896,894,000
1999-01-20$7.96$7.962,295,000
1999-01-19$8.08$8.085,175,600
1999-01-15$8.50$8.504,648,200
1999-01-14$8.04$8.044,140,000
1999-01-13$7.72$7.722,120,400
1999-01-12$7.50$7.504,279,200
1999-01-11$7.19$7.19949,200
1999-01-08$7.27$7.272,253,000
1999-01-07$7.13$7.133,339,600
1999-01-06$7.00$7.003,258,000
1999-01-05$7.38$7.382,304,000
1999-01-04$7.79$7.792,570,400