| 6.28% | % of Shares Held by All Insider |
| 0.00% | % of Shares Held by Institutions |
| 0.00% | % of Float Held by Institutions |
| 0 | Number of Institutions Holding Shares |
| Holder | Shares | Date Reported | % Out | Value |
|---|---|---|---|---|
| TRV GP III, LLC | 6,391,176 | Mar 30, 2019 | 17.35% | 122,327,108 |
| BB Biotech Ag | 2,865,841 | Mar 30, 2019 | 7.78% | 54,852,196 |
| Partner Fund Management, L.P. | 1,951,061 | Mar 30, 2019 | 5.30% | 37,343,307 |
| Blackrock Inc. | 1,893,972 | Mar 30, 2019 | 5.14% | 36,250,624 |
| Armistice Capital, LLC | 1,536,000 | Mar 30, 2019 | 4.17% | 29,399,040 |
| Vanguard Group, Inc. (The) | 1,391,775 | Mar 30, 2019 | 3.78% | 26,638,573 |
| Casdin Capital, LLC | 1,128,075 | Mar 30, 2019 | 3.06% | 21,591,355 |
| Farallon Capital Management LLC | 1,000,158 | Mar 30, 2019 | 2.72% | 19,143,024 |
| FMR, LLC | 737,562 | Mar 30, 2019 | 2.00% | 14,116,936 |
| Highline Capital Management, L.P. | 588,797 | Mar 30, 2019 | 1.60% | 11,269,574 |
| Holder | Shares | Date Reported | % Out | Value |
|---|---|---|---|---|
| Fidelity Select Portfolios - Biotechnology | 737,162 | Mar 30, 2019 | 2.00% | 14,109,280 |
| Mutual Fund Ser Tr-Eventide Healthcare & Life Sciences Fund | 703,425 | Sep 29, 2018 | 1.91% | 13,308,801 |
| Vanguard Total Stock Market Index Fund | 614,373 | Sep 29, 2018 | 1.67% | 11,623,937 |
| iShares Russell 2000 ETF | 434,636 | Apr 29, 2019 | 1.18% | 9,170,819 |
| iShares NASDAQ Biotechnology ETF | 381,248 | Apr 29, 2019 | 1.04% | 8,044,332 |
| Vanguard Extended Market Index Fund | 334,319 | Dec 30, 2018 | 0.91% | 3,142,598 |
| Legg Mason Clearbridge Aggressive Growth Fd | 229,702 | Mar 30, 2019 | 0.62% | 4,396,496 |
| iShares Russell 2000 Growth ETF | 183,360 | Apr 29, 2019 | 0.50% | 3,868,896 |
| JP Morgan U.S. Small Company Fund | 168,550 | Apr 29, 2019 | 0.46% | 3,556,405 |
| Advanced Series Tr-AST Small Cap Growth Port | 152,147 | Sep 29, 2018 | 0.41% | 2,878,621 |