EcoR1 Capital, LLC: ANAPTYSBIO INC (ANAB): Quarterly 13F Position History
As of Q1 2026, EcoR1 Capital, LLC reported 7,880,094 shares of ANAPTYSBIO INC (ANAB), worth $437.0M and representing 18.7% of its 13F equity book. The position first appeared in Q4 2019 and has been disclosed across 26 13F-HR filings in Pactolio's tracked window.
- 7,880,094Shares Held (Latest Filing)
- $437.0MReported Market Value (Latest Filing)
- 18.7%Portfolio Weight (% of 13F Equity Book)
- 0Quarter-over-Quarter Share Change
- +$55.0MQuarter-over-Quarter Value Change
- 7,880,094Peak Reported Shares (Historical)
Quarterly 13F-HR Disclosure History Source: SEC 13F-HR filings, 26 quarter s
| Quarter | Shares | QoQ Share Change | Share Change (%) | Market Value | Weight | Implied Price |
|---|---|---|---|---|---|---|
| Q1 2026 | 7,880,094 | 0 | — | $437.0M | 18.7% | $55.5 |
| Q4 2025 | 7,880,094 | 0 | — | $382.0M | 17.4% | $48.5 |
| Q3 2025 | 7,880,094 | 0 | — | $241.3M | 11.6% | $30.6 |
| Q2 2025 | 7,880,094 | 0 | — | $174.9M | 10.4% | $22.2 |
| Q1 2025 | 7,880,094 | +6,646 | +0.1% | $146.5M | 8.7% | $18.6 |
| Q4 2024 | 7,873,448 | +78,452 | +1.0% | $104.2M | 4.2% | $13.2 |
| Q3 2024 | 7,794,996 | +273,972 | +3.6% | $261.1M | 8.9% | $33.5 |
| Q2 2024 | 7,521,024 | 0 | — | $188.5M | 5.8% | $25.1 |
| Q1 2024 | 7,521,024 | 0 | — | $169.4M | 4.3% | $22.5 |
| Q4 2023 | 7,521,024 | 0 | — | $161.1M | 4.2% | $21.4 |
| Q3 2023 | 7,521,024 | 0 | — | $135.1M | 4.6% | $18.0 |
| Q2 2023 | 7,521,024 | 0 | — | $153.0M | 4.0% | $20.3 |
| Q1 2023 | 7,521,024 | 0 | — | $163.7M | 5.3% | $21.8 |
| Q4 2022 | 7,521,024 | 0 | — | $233.1M | 7.1% | $31.0 |
| Q3 2022 | 7,521,024 | 0 | — | $191.9M | 5.7% | $25.5 |
| Q2 2022 | 7,521,024 | 0 | — | $152.7M | 5.3% | $20.3 |
| Q1 2022 | 7,521,024 | 0 | — | $186.1M | 5.8% | $24.7 |
| Q4 2021 | 7,521,024 | 0 | — | $261.4M | 8.3% | $34.8 |
| Q3 2021 | 7,521,024 | 0 | — | $204.0M | 7.2% | $27.1 |
| Q2 2021 | 7,521,024 | +369,400 | +5.2% | $195.0M | 7.3% | $25.9 |
| Q1 2021 | 7,151,624 | +3,928,300 | +121.9% | $154.1M | 6.9% | $21.5 |
| Q4 2020 | 3,223,324 | 0 | — | $69.3M | 3.9% | $21.5 |
| Q3 2020 | 3,223,324 | +148,310 | +4.8% | $47.5M | 3.4% | $14.8 |
| Q2 2020 | 3,075,014 | +39,000 | +1.3% | $68.7M | 5.1% | $22.3 |
| Q1 2020 | 3,036,014 | +1,069,914 | +54.4% | $42.9M | 4.5% | $14.1 |
| Q4 2019 | 1,966,100 | — | — | $31.9M | 3.1% | $16.2 |
Methodology & FAQ
How This Position History Is Sourced
Each row is one SEC Form 13F-HR filing disclosing this position. Share count, market value, and reported quarter are taken verbatim from the filing; portfolio weight is recomputed against the same filing's total reported equity book. Implied price-per-share is market value divided by shares — a quarter-end mark, not the manager's cost basis. See the full methodology document for the normalization rules.
When did EcoR1 Capital, LLC first disclose a ANAB position in 13F-HR filings?
EcoR1 Capital, LLC first reported ANAPTYSBIO INC (ANAB) on its 13F-HR filing for the period ending 2019-12-31 (Q4 2019). The position has appeared on 26 reported quarters within Pactolio's tracked window.
What was EcoR1 Capital, LLC's most recent quarter-over-quarter share-count change in ANAB?
EcoR1 Capital, LLC held the same 7,880,094 shares of ANAB between Q4 2025 and Q1 2026 — the reported share count was unchanged quarter-over-quarter.
Does the implied price-per-share represent EcoR1 Capital, LLC's cost basis in ANAB?
No. The implied price-per-share column is the 13F-HR reported market value divided by reported share count on the filing date (end of quarter). It is a quarter-end mark, not a cost basis or transaction price. Use it as a sanity check on the value column, not as an indicator of the manager's entry or exit price.