BAKER BROS. ADVISORS LP

Baker Bros Advisors' $17.1B Q4 2025 13F is one of the most concentrated healthcare books in the dataset, with 86 positions and a top-five weighting of 58.5%. The manager added three new $1B+ names — Madrigal Pharmaceuticals ($12.5B market cap), Insmed ($4.5B), and Acadia Pharmaceuticals ($3.3B) — while reducing the prior quarter's largest holding, BeOne Medicines, from 29.5% to 15.7% of the book. The $7B AUM increase from $10.2B to $17.1B reflects inflows rather than new capital calls. The changes block shows 15 new positions and 15 sales, with the largest additions in NASH (MDGL), pulmonary/immunology (INSM), and CNS (ACAD). The whaleScore of 74.50 reflects the absolute scale of a concentrated biotech investor, not diversification.