EcoR1 Capital, LLC 13F: Portfolio & Holdings

A Form 13F-HR filed by EcoR1 Capital with the U.S. SEC discloses all long positions in Section 13(f) securities — U.S.-listed equities, ETFs, closed-end funds, and listed put/call options — held at quarter-end with a market value of at least $200,000 or 10,000 or more shares. Pactolio aggregates these filings to surface the manager’s reported portfolio weights, share counts, and quarter-over-quarter portfolio changes in a structured format. The filing represents a point-in-time snapshot of disclosed long-side exposure, not a real-time or complete view of the fund’s total book.

Conviction is measured by portfolio weight — the percentage of EcoR1 Capital’s total reported 13F market value allocated to a given position — rather than by absolute share count or dollar value alone. A position representing a disproportionately large share of the fund’s disclosed book signals high-conviction allocation, regardless of whether it ranks among the fund’s largest absolute holdings.

SEC Form 13F requires disclosure of long positions only. Specifically excluded are: short interest, total return swaps, credit default swaps, and all OTC derivatives — none of which appear in 13F filings regardless of position size. Listed put and call options must be disclosed but are excluded from portfolio weight calculations on this platform so that reported weights reflect direct equity exposure and remain comparable across filers. This means EcoR1 Capital’s 13F represents the reported long book, which may differ materially from its net economic exposure.

Investment managers must submit Form 13F within 45 calendar days of each quarter-end (the T+45 deadline). Pactolio ingests filings directly from SEC EDGAR as they are published — managers who file early appear in our system before the deadline, while late filers are captured on their actual filing date. The quarter label shown at the top of this page reflects the most recently processed 13F cycle for EcoR1 Capital. The inherent reporting lag means the data always reflects positions as of the prior quarter-end, not current holdings.

Under SEC Rule 13f-1, any investment manager — including hedge funds, family offices, registered investment advisers, pension funds, and university endowments — that exercises investment discretion over $100 million or more in Section 13(f) securities at any point during a calendar year must file Form 13F for that year. EcoR1 Capital meets this threshold, which is why its holdings are publicly disclosed and accessible on this platform. The $100 million threshold is evaluated on a rolling basis, meaning new filers can enter and existing filers can exit the disclosure regime as AUM crosses that boundary.