BAKER BROS. ADVISORS LP — Quarter-over-Quarter 13F Allocation Shifts Q1 2026
In Q1 2026, BAKER BROS. ADVISORS LP initiated 7 new positions, increased allocation to 10 existing positions, trimmed 6 positions, and exited 9 positions entirely. The fund's 13F equity book grew from $17.08B to $17.42B (+2.0% QoQ) . All deltas are sourced from sequential SEC Form 13F-HR filings; share-count changes reflect explicit trading activity, while weight changes can also include price movement. This page lists every position change reported — the portfolio overview shows a summary of the top shifts.
Net Portfolio Value Change
- $17.08BPrior quarter
- $17.42BCurrent quarter
- + $0.34BNet delta
- +2.0%% change
New Position Initiations Q1 2026
Securities disclosed for the first time in Q1 2026 that were not present in the prior 13F-HR filing.
| Company | Ticker | Initial Allocation Weight | History |
|---|---|---|---|
| MIRUM PHARMACEUTICALS INC | MIRM | 0.24% | Holders → |
| EVOMMUNE, INC. | EVMN | 0.11% | Holders → |
| AKTIS ONCOLOGY, INC. | AKTS | 0.10% | Holders → |
| GENERATE BIOMEDICINES, INC. | GENB | 0.10% | Holders → |
| COMPASS PATHWAYS PLC | CMPS | 0.07% | Holders → |
| EIKON THERAPEUTICS, INC. | EIKN | 0.03% | Holders → |
| VERASTEM | VSTM | 0.02% | Holders → |
Largest Allocation Increases Q1 2026
Largest portfolio-weight increases in existing positions. Share-count delta is shown separately so price-only re-weighting can be distinguished from active adds.
| Company | Ticker | Δ Weight | Δ Shares | History |
|---|---|---|---|---|
| ENLIVEN THERAPEUTICS INC | ELVN | +0.18% | +233.52% | Holders → |
| WAVE LIFE SCIENCES LTD. | WVE | +-0.00% | +139.10% | Holders → |
| GRAIL, INC. | GRAL | +0.15% | +93.19% | Holders → |
| PRAXIS PRECISION MEDICINES I | PRAX | +1.30% | +55.63% | Holders → |
| ARCUS BIOSCIENCES, INC. | RCUS | +0.01% | +53.93% | Holders → |
| CRINETICS PHARMACEUTICALS, INC. | CRNX | +0.04% | +42.61% | Holders → |
| ALUMIS INC. | ALMS | +0.17% | +28.80% | Holders → |
| CYTOMX THERAPEUTICS, INC. | CTMX | +0.03% | +17.06% | Holders → |
| DESIGN THERAPEUTICS, INC. | DSGN | +0.04% | +15.80% | Holders → |
| IONIS PHARMACEUTICALS INC. | IONS | +0.05% | +14.28% | Holders → |
Largest Allocation Reductions Q1 2026
Largest portfolio-weight decreases in existing positions (positions kept open at a lower allocation).
| Company | Ticker | Δ Weight | Δ Shares | History |
|---|---|---|---|---|
| IMMUNOCORE HOLDINGS PLC | IMCR | -0.34% | -68.38% | Holders → |
| BIONTECH SE | BNTX | -0.14% | -67.54% | Holders → |
| TECTONIC THERAPEUTIC INC | TECX | -0.00% | -32.72% | Holders → |
| ROIVANT SCIENCES LTD. | ROIV | 0.07% | -12.37% | Holders → |
| IMMATICS NV | IMTX | -0.13% | -9.74% | Holders → |
| ARROWHEAD PHARMACEUTICALS INC | ARWR | -0.13% | -8.40% | Holders → |
Exited Positions Q1 2026
Positions present in the prior 13F-HR filing that no longer appear in Q1 2026.
| Company | Ticker | Last-Reported Portfolio Weight |
|---|---|---|
| ULTRAGENYX PHARMACEUTICAL IN | RARE | 0.37% |
| TERNS PHARMACEUTICALS INC | TERN | 0.22% |
| BIOCRYST PHARMACEUTICALS INC | BCRX | 0.13% |
| VENTYX BIOSCIENCES, INC. | SYN_92332V107 | 0.12% |
| NUVALENT INC | NUVL | 0.08% |
| 4D MOLECULAR THERAPEUTICS IN | FDMT | 0.02% |
| VIR BIOTECHNOLOGY INC | VIR | 0.02% |
| KALA BIO, INC. | KALA | 0.01% |
| ACRIVON THERAPEUTICS, INC. | ACRV | 0.00% |
Methodology & FAQ
How BAKER BROS. ADVISORS LP Quarterly Changes Are Computed
Each row above is computed by joining the most recent 13F-HR filing for BAKER BROS. ADVISORS LP against the immediately preceding quarterly filing for the same fund. Portfolio weights are normalized to exclude listed options for comparability. A complete description of the methodology — including how confidential treatment filings are handled and why share count rather than weight is the cleaner trading signal — is documented in the Methodology.
Which positions did BAKER BROS. ADVISORS LP initiate in Q1 2026?
BAKER BROS. ADVISORS LP established 7 new positions in Q1 2026: MIRUM PHARMACEUTICALS INC (MIRM, 0.24%), EVOMMUNE, INC. (EVMN, 0.11%), AKTIS ONCOLOGY, INC. (AKTS, 0.10%), GENERATE BIOMEDICINES, INC. (GENB, 0.10%), COMPASS PATHWAYS PLC (CMPS, 0.07%), EIKON THERAPEUTICS, INC. (EIKN, 0.03%), VERASTEM (VSTM, 0.02%).
Which existing positions saw the largest allocation increases for BAKER BROS. ADVISORS LP in Q1 2026?
The largest portfolio-weight increases in existing positions were: ENLIVEN THERAPEUTICS INC (ELVN, +0.18% weight, +233.52% shares), WAVE LIFE SCIENCES LTD. (WVE, +-0.00% weight, +139.10% shares), GRAIL, INC. (GRAL, +0.15% weight, +93.19% shares), PRAXIS PRECISION MEDICINES I (PRAX, +1.30% weight, +55.63% shares), ARCUS BIOSCIENCES, INC. (RCUS, +0.01% weight, +53.93% shares), CRINETICS PHARMACEUTICALS, INC. (CRNX, +0.04% weight, +42.61% shares), ALUMIS INC. (ALMS, +0.17% weight, +28.80% shares), CYTOMX THERAPEUTICS, INC. (CTMX, +0.03% weight, +17.06% shares), DESIGN THERAPEUTICS, INC. (DSGN, +0.04% weight, +15.80% shares), IONIS PHARMACEUTICALS INC. (IONS, +0.05% weight, +14.28% shares).
Which positions did BAKER BROS. ADVISORS LP fully exit in Q1 2026?
BAKER BROS. ADVISORS LP fully exited 9 positions in Q1 2026: ULTRAGENYX PHARMACEUTICAL IN (RARE, last-reported weight 0.37%), TERNS PHARMACEUTICALS INC (TERN, last-reported weight 0.22%), BIOCRYST PHARMACEUTICALS INC (BCRX, last-reported weight 0.13%), VENTYX BIOSCIENCES, INC. (SYN_92332V107, last-reported weight 0.12%), NUVALENT INC (NUVL, last-reported weight 0.08%), 4D MOLECULAR THERAPEUTICS IN (FDMT, last-reported weight 0.02%), VIR BIOTECHNOLOGY INC (VIR, last-reported weight 0.02%), KALA BIO, INC. (KALA, last-reported weight 0.01%), ACRIVON THERAPEUTICS, INC. (ACRV, last-reported weight 0.00%).
Which existing positions saw the largest allocation reductions for BAKER BROS. ADVISORS LP in Q1 2026?
The largest portfolio-weight reductions in positions kept open were: IMMUNOCORE HOLDINGS PLC (IMCR, -0.34% weight, -68.38% shares), BIONTECH SE (BNTX, -0.14% weight, -67.54% shares), TECTONIC THERAPEUTIC INC (TECX, -0.00% weight, -32.72% shares), ROIVANT SCIENCES LTD. (ROIV, 0.07% weight, -12.37% shares), IMMATICS NV (IMTX, -0.13% weight, -9.74% shares), ARROWHEAD PHARMACEUTICALS INC (ARWR, -0.13% weight, -8.40% shares).
Do quarter-over-quarter 13F allocation changes constitute explicit trading signals?
No. Quarter-over-quarter changes reflect a combination of active trading and market price movement. A weight increase can result from price appreciation alone, without the manager adding shares. Share-count delta is the cleaner indicator of explicit trading activity.