Bain Capital Life Sciences Investors, LLC — 13F Holdings & Portfolio
CIK 1703031 · latest 13F-HR filed 2026-08-14
Bain Capital Life Sciences Investors, LLC manages $1.68B in 13F-reported U.S. long-equity assets across 21 reported positions as of its 2026-06-30 13F-HR filing. Its largest disclosed positions are KLRA (29.58%), HTFL (14.74%), NAMS (7.67%). Quarter over quarter (versus its 2026-03-31 filing) the fund opened 2 new positions, exited 1, added to 11, and trimmed 6.
AUM is the long-equity portion reported on Form 13F-HR. Excludes short positions, cash, foreign holdings, and non-13F assets. For informational purposes only — not investment advice.
BOSTON, MA 02116
$1.68B
Long-equity book
21
Distinct positions
2026-06-30
Filed 2026-08-14
+2 / −1 / ↑11 / ↓6
vs 2026-03-31
| Name | Title / Status | Ownership | Type |
|---|
Top Adds (vs prior quarter)
- ALKERMES PLC$80.0M +370.7%
- CABALETTA BIO INC$27.6M +106.0%
- SOLID BIOSCIENCES INC$27.4M +38.7%
- PHARVARIS N V$16.9M +22.4%
- C4 THERAPEUTICS INC$14.6M +77.6%
Top Trims
- NEWAMSTERDAM PHARMA COMPANY-$104.9M -44.8%
- OLEMA PHARMACEUTICALS INC-$22.8M -20.5%
- RAPID MICRO BIOSYSTEMS INC-$4.6M -23.8%
- UPSTREAM BIO INC-$3.6M -46.7%
- ANNEXON INC-$3.5M -12.3%
Rows tagged Call or Put are options positions, not stock. Per SEC Form 13F-HR, Value shows the notional value of the underlying (shares covered × underlying price), not the option premium. Shares is the number of underlying shares covered (divide by 100 for contract count).
| # | Issuer | Symbol | CUSIP | Value | Weight | Shares | Type |
|---|---|---|---|---|---|---|---|
| 1 | KAILERA THERAPEUTICS INC | KLRA | 482931102 | $497.5M | 29.58% | 22,583,268 | SH |
| 2 | HEARTFLOW INC | HTFL | 42238D107 | $247.9M | 14.74% | 8,448,158 | SH |
| 3 | NEWAMSTERDAM PHARMA COMPANY | NAMS | N62509109 | $129.0M | 7.67% | 3,806,566 | SH |
| 4 | SAVARA INC | SVRA | 805111101 | $108.4M | 6.45% | 17,600,621 | SH |
| 5 | ALKERMES PLC | ALKS | G01767105 | $101.5M | 6.04% | 1,937,938 | SH |
| 6 | SOLID BIOSCIENCES INC | SLDB | 83422E204 | $98.0M | 5.83% | 9,808,819 | SH |
| 7 | PHARVARIS N V | PHVS | N69605108 | $92.5M | 5.50% | 2,675,509 | SH |
| 8 | OLEMA PHARMACEUTICALS INC | OLMA | 68062P106 | $88.6M | 5.27% | 7,085,249 | SH |
| 9 | HEMAB THERAPEUTICS HOLDINGS INC | COAG | 423494103 | $60.6M | 3.60% | 1,650,000 | SH |
| 10 | CABALETTA BIO INC | CABA | 12674W109 | $53.6M | 3.19% | 17,241,445 | SH |
| 11 | X4 PHARMACEUTICALS INC | XFOR | 98420X202 | $37.2M | 2.21% | 7,967,454 | SH |
| 12 | DIANTHUS THERAPEUTICS INC | DNTH | 252828108 | $35.3M | 2.10% | 362,470 | SH |
| 13 | C4 THERAPEUTICS INC | CCCC | 12529R107 | $33.5M | 1.99% | 7,171,910 | SH |
| 14 | KYVERNA THERAPEUTICS INC | KYTX | 501976104 | $25.7M | 1.53% | 2,885,000 | SH |
| 15 | ANNEXON INC | ANNX | 03589W102 | $25.3M | 1.51% | 4,437,731 | SH |
| 16 | RAPID MICRO BIOSYSTEMS INC | RPID | 75340L104 | $14.6M | 0.87% | 8,434,560 | SH |
| 17 | DISC MEDICINE INC | IRON | 254604101 | $10.3M | 0.61% | 141,234 | SH |
| 18 | ATEA PHARMACEUTICALS INC | AVIR | 04683R106 | $9.7M | 0.57% | 2,075,639 | SH |
| 19 | XILIO THERAPEUTICS INC | XLO | 98422T209 | $6.4M | 0.38% | 664,021 | SH |
| 20 | UPSTREAM BIO INC | UPB | 91678A107 | $4.2M | 0.25% | 600,949 | SH |
| 21 | NEWAMSTERDAM PHARMA COMPANY | NAMSW | N62509117 | $2.1M | 0.13% | 99,999 | SH |
| Period | Filed | AUM | Holdings | Accession |
|---|---|---|---|---|
| 2026-06-30 | 2026-08-14 | $1.68B | 21 | 0001193125-26-350470 |
| 2026-03-31 | 2026-05-15 | $1.11B | 20 | 0001193125-26-226961 |
| 2025-12-31 | 2026-02-17 | $1.31B | 19 | 0001193125-26-054833 |
| 2025-09-30 | 2025-11-14 | $1.51B | 21 | 0001193125-25-283094 |