Baker Bros. Advisors, a hedge fund that lists Yale University’s endowment and the Tisch family among its clients, added a new stake in InVitae in the second quarter and cut back on its top holding Seagen. Founded by brothers Julian and Felix Baker in 2000, the health care hedge fund focuses on biotech and life sciences investing. The founders, who have a background in immunology, used their experience to capitalize in the sector’s boom over the past decade. The portfolio has 110 holdings and a very low turnover rate. Baker Bros. built a significant new stake in Invitae in the second quarter, according to InsiderScore. The genetic testing company is the hedge fund’s eighth-largest holding, valued at $135 million. But the stock has slid 44% this year. The hedge fund added to Acadia Pharmaceuticals , its fourth-largest holding, increasing the stake by 2.2%. The biotech stock with a focus on neuroscience has surged more than 84% this year. Baker Bros. doubled down on its bet in Kymera Therapeutics , which it raised by more than 51%. The biotech stock is down 21% this year. The hedge fund also took new stakes in ImmunoGen , which has more than tripled this year, soaring 216%, and Day One Biopharmaceuticals , which is down by 34%. Another new holding is Cogent Biosciences , which is up by just 7%. However, Baker Bros. notably took some profits in its largest holding Seagen in the second quarter after the stock surged 51% this year. The hedge fund lowered its exposure to the biotech company, which develops treatments for cancer, by 5%. Still, Seagen remains Baker Brothers’ No. 1 holding, valued at roughly $8.6billion as of the end of June. Instead, — CNBC’s Yun Li contributed to this report.