Ownership Profile

Top Holders

Holder Shares Held % O/S Share Change Filing Date
Fidelity Management & Research Company 20,501,150 14.81 45,911 12/31/18
The Vanguard Group, Inc. 11,829,388 8.55 738,090 12/31/18
Biogen Idec Inc 11,501,153 8.31 11,501,153 6/5/18
ClearBridge Investments, LLC 10,380,319 7.50 143,380 12/31/18
Bellevue Asset Management AG 9,123,922 6.59 147,052 12/31/18
Baillie Gifford & Co. 8,750,014 6.32 -208,099 12/31/18
Wellington Management Company, LLP 7,627,005 5.51 -1,668,160 12/31/18
BlackRock Institutional Trust Company, N.A. 7,051,017 5.09 176,101 12/31/18
Ivy Investment Management Company 3,498,062 2.53 -334,649 12/31/18
State Street Global Advisors (US) 2,535,169 1.83 -479,547 12/31/18

Top Holders: Mutual Funds

Fund Shares Held % O/S Share Change Filing Date
BB Biotech Fd 8,741,334 6.32 75,000 12/31/18
Fidelity Growth Company Fund 7,964,392 5.75 49,988 1/31/19
Vanguard Total Stock Market Index Fund 3,336,232 2.41 40,664 2/28/19
Ivy Science and Technology Fund 3,217,526 2.32 -316,475 12/31/18
Vanguard Small-Cap Index Fund 3,212,034 2.32 31,708 2/28/19
ClearBridge Aggressive Growth Fund 2,722,745 1.97 -- 12/31/18
Fidelity Select Biotechnology Portfolio 2,524,877 1.82 -- 1/31/19
Fidelity Series Growth Company Fund 2,165,279 1.56 16,900 1/31/19
Hartford MidCap Fund 2,121,070 1.53 27,284 1/31/19
Vanguard Health Care Fund 2,119,180 1.53 -- 12/31/18

* Insider values reflect direct beneficial ownership.

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