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 — 1991

DateSplit-adjusted closeCumulative dividend-reinvested closeReported volumeOpen priceExchange Volume
1991-12-31$2.17$2.17460,800
1991-12-30$2.29$2.29384,000
1991-12-27$2.13$2.13116,400
1991-12-26$2.08$2.0899,000
1991-12-24$2.17$2.1737,200
1991-12-23$2.25$2.25119,400
1991-12-20$2.17$2.17321,000
1991-12-19$2.29$2.2982,200
1991-12-18$2.33$2.3357,000
1991-12-17$2.42$2.42100,200
1991-12-16$2.46$2.4690,600
1991-12-13$2.46$2.46246,600
1991-12-12$2.46$2.46181,200
1991-12-11$2.33$2.33439,800
1991-12-10$2.04$2.04483,600
1991-12-09$2.04$2.04204,600
1991-12-06$1.96$1.9658,800
1991-12-05$2.04$2.04410,400
1991-12-04$2.00$2.00370,200
1991-12-03$2.06$2.06910,800
1991-12-02$2.13$2.13833,400
1991-11-29$2.00$2.0060,000
1991-11-27$1.96$1.96192,600
1991-11-26$1.88$1.88199,200
1991-11-25$2.08$2.08323,400
1991-11-22$2.08$2.081,123,800
1991-11-21$2.25$2.25208,800
1991-11-20$2.21$2.21434,400
1991-11-19$2.38$2.382,037,000
1991-11-18$2.46$2.462,312,400
1991-11-15$2.38$2.381,191,000
1991-11-14$2.98$2.981,420,200
1991-11-13$2.92$2.921,289,400
1991-11-12$2.92$2.92776,400
1991-11-11$2.71$2.71818,400
1991-11-08$2.71$2.711,528,200
1991-11-07$2.54$2.54601,200
1991-11-06$2.67$2.67443,400
1991-11-05$2.75$2.75716,400
1991-11-04$2.96$2.96270,000
1991-11-01$3.04$3.041,586,400
1991-10-31$3.08$3.08178,200
1991-10-30$3.17$3.17277,200
1991-10-29$3.17$3.17162,600
1991-10-28$2.96$2.96292,200
1991-10-25$3.00$3.00243,600
1991-10-24$3.08$3.08164,400
1991-10-23$3.17$3.17540,000
1991-10-22$3.25$3.2584,600
1991-10-21$3.29$3.29196,800
1991-10-18$3.38$3.38764,400
1991-10-17$3.17$3.17954,600
1991-10-16$3.54$3.541,215,600
1991-10-15$3.31$3.31779,400
1991-10-14$2.96$2.96369,600
1991-10-11$2.69$2.69312,000
1991-10-10$2.56$2.561,455,600
1991-10-09$2.52$2.52469,200
1991-10-08$2.54$2.544,804,200
1991-10-07$2.67$2.67605,400
1991-10-04$2.88$2.88303,000
1991-10-03$2.96$2.96246,600
1991-10-02$3.17$3.17409,800
1991-10-01$3.08$3.08112,800
1991-09-30$3.13$3.13594,600
1991-09-27$3.33$3.33779,400
1991-09-26$3.17$3.17598,800
1991-09-25$3.04$3.04473,400
1991-09-24$3.00$3.001,826,400
1991-09-23$2.96$2.961,954,800
1991-09-20$3.08$3.082,092,800
1991-09-19$3.15$3.151,717,800
1991-09-18$3.13$3.131,704,000
1991-09-17$3.13$3.1317,096,400