Bain Capital Life Sciences Investors, LLC holds a concentrated book of 21 reported positions worth $1.7B as of Q2 2026 (disclosed Aug 14, 2026, a ~45-day 13F lag). This quarter Kailera Therapeutics Inc first appears in 13F filings (one of 2 new listings in the book), a listing rather than a purchase; they trimmed Heartflow Inc. Their largest long position is Kailera Therapeutics Inc at 30% of the reported non-option book.
Top-heavy: concentrated book
Share of the disclosed book in its largest positions. A higher top-5 share means a more concentrated, higher-conviction portfolio.
100% mapped to company sectors
Direct operating-company sectors from our SIC-based security master. ETF/fund and unclassified holdings stay visible separately; this is not ETF look-through exposure.
Estimated $ traded · quarter-end prices (an exit at the prior quarter-end), no cost basis
Other tracked managers holding the same core names as Bain Capital Life Sciences Investors, LLC
| Manager / fund | Shared names | Their $ in those |
|---|---|---|
| Avidity Partners Management LP | 3 / 21 | $207.2M |
| Atlas Venture Life Science Advisors, LLC | 2 / 21 | $224.6M |
| Octagon Capital Advisors LP | 3 / 21 | $215.1M |
| Frazier Life Sciences Management, L.P. | 7 / 21 | $847.7M |
| Saturn V Capital Management LP | 3 / 21 | $116.4M |
| Spruce Street Capital LP | 3 / 21 | $84.4M |
| Kalehua Capital Management LLC | 2 / 21 | $24.3M |
| Foresite Capital Management V, LLC | 2 / 21 | $50.3M |
Ranked by the share of each fund's own book sitting in the names it shares with Bain Capital Life Sciences Investors, LLC: only funds sharing at least a tenth of the book qualify. Index giants, bank custody books and market makers are excluded. They hold everything, so their overlap says nothing.
Bars show each position's share of the portfolio. Click a row for its position history.
| # | Security | Value | Shares | % Port | Last move | History |
|---|---|---|---|---|---|---|
| 1 | Kailera Therapeutics Inc COMMON STOCK | $497.5M | 22.58M | 29.6% | →Listed Newly reportable | |
| 2 | Heartflow Inc COM | $247.9M | 8.45M | 14.7% | ▼−19% Reduced · −2.0M sh | |
| 3 | Newamsterdam Pharma Company ORDINARY SHARES | $129.0M | 3.81M | 7.7% | ▼−48% Reduced · −3.5M sh | |
| 4 | Savara Inc COM | $108.4M | 17.60M | 6.4% | —Held | |
| 5 | Alkermes PLC SHS | $101.5M | 1.94M | 6.0% | ▲+218% Added · +1.3M sh | |
| 6 | Solid Biosciences Inc COM NEW | $98.0M | 9.81M | 5.8% | —Held | |
| 7 | Pharvaris N V COM | $92.5M | 2.68M | 5.5% | —Held | |
| 8 | Olema Pharmaceuticals Inc COM | $88.6M | 7.09M | 5.3% | ▼−5.2% Reduced · −388K sh | |
| 9 | Hemab Therapeutics Holdings Inc COM SHS | $60.6M | 1.65M | 3.6% | →Listed Newly reportable | |
| 10 | Cabaletta Bio Inc COM | $53.6M | 17.24M | 3.2% | ▲+78% Added · +7.6M sh | |
| 11 | X4 Pharmaceuticals Inc COM NEW | $37.2M | 7.97M | 2.2% | —Held | |
| 12 | Dianthus Therapeutics Inc COM | $35.3M | 362.5K | 2.1% | —Held | |
| 13 | C4 Therapeutics Inc COM STK | $33.5M | 7.17M | 2.0% | —Held | |
| 14 | Kyverna Therapeutics Inc COM | $25.7M | 2.88M | 1.5% | ▼−7.2% Reduced · −225K sh | |
| 15 | Annexon Inc COM | $25.3M | 4.44M | 1.5% | ▼−15% Reduced · −775K sh | |
| 16 | Rapid Micro Biosystems Inc CLASS A COM | $14.6M | 8.43M | 0.9% | —Held | |
| 17 | Disc Medicine Inc COM | $10.3M | 141.2K | 0.6% | —Held | |
| 18 | Atea Pharmaceuticals Inc COM | $9.7M | 2.08M | 0.6% | ▼−12% Reduced · −285K sh | |
| 19 | Xilio Therapeutics Inc COM | $6.4M | 664.0K | 0.4% | —Held | |
| 20 | Upstream Bio Inc COM | $4.2M | 600.9K | 0.2% | ▼−31% Reduced · −266K sh | |
| 21 | Newamsterdam Pharma Company *W EXP 99/99/999 | $2.1M | 100.0K | 0.1% | —Held |
This fund page is the Follow view. The Build view lets your agent pull holdings, quarter changes, overlap, and source filings through API or MCP.
curl -H "Authorization: Bearer YOUR_API_KEY" \ "https://arkolith.com/api/v1/funds/1703031/holdings"
Use Arkolith to show Bain Capital Life Sciences Investors, LLC's latest holdings, largest changes, and filing provenance.
As-of date vs the date the SEC received each filing
Reported 13F total per quarter. Raw filing totals can include option notional.
| Quarter | As of | Filed | Lag | Positions | Value | Form |
|---|---|---|---|---|---|---|
| Q2 2026 | Jun 30, 2026 | Aug 14, 2026 | 45d | 21 | $1.7B | 13F-HR |
| Q1 2026 | Mar 31, 2026 | May 15, 2026 | 45d | 20 | $1.1B | 13F-HR |
| Q4 2025 | Dec 31, 2025 | Feb 17, 2026 | 48d | 19 | $1.3B | 13F-HR |
| Q3 2025 | Sep 30, 2025 | Nov 14, 2025 | 45d | 21 | $1.5B | 13F-HR |
| Q2 2025 | Jun 30, 2025 | Aug 14, 2025 | 45d | 23 | $799.3M | 13F-HR |
| Q1 2025 | Mar 31, 2025 | May 15, 2025 | 45d | 24 | $675.9M | 13F-HR |
| Q4 2024 | Dec 31, 2024 | Feb 14, 2025 | 45d | 26 | $850.1M | 13F-HR |
| Q3 2024 | Sep 30, 2024 | Nov 14, 2024 | 45d | 24 | $961.2M | 13F-HR |
| Q2 2024 | Jun 30, 2024 | Aug 12, 2024 | 43d | 25 | $910.8M | 13F-HR |
| Q1 2024 | Mar 31, 2024 | May 15, 2024 | 45d | 26 | $1.2B | 13F-HR |
| Q4 2023 | Dec 31, 2023 | Feb 13, 2024 | 44d | 27 | $1.0B | 13F-HR |
| Q3 2023 | Sep 30, 2023 | Nov 14, 2023 | 45d | 31 | $894.2M | 13F-HR |
| Q2 2023 | Jun 30, 2023 | Aug 14, 2023 | 45d | 32 | $971.0M | 13F-HR |
| Q1 2023 | Mar 31, 2023 | May 15, 2023 | 45d | 34 | $800.1M | 13F-HR |
| Q4 2022 | Dec 31, 2022 | Feb 14, 2023 | 45d | 33 | $894.8M | 13F-HR |
| Q3 2022 | Sep 30, 2022 | Nov 14, 2022 | 45d | 33 | $837.8M | 13F-HR |
| Q2 2022 | Jun 30, 2022 | Aug 15, 2022 | 46d | 35 | $852.7M | 13F-HR |
| Q1 2022 | Mar 31, 2022 | May 16, 2022 | 46d | 34 | $1.0B | 13F-HR |
| Q4 2021 | Dec 31, 2021 | Feb 14, 2022 | 45d | 34 | $1.3B | 13F-HR |
| Q3 2021 | Sep 30, 2021 | Nov 15, 2021 | 46d | 33 | $1.6B | 13F-HR |
| Q2 2021 | Jun 30, 2021 | Aug 16, 2021 | 47d | 30 | $1.5B | 13F-HR |
| Q1 2021 | Mar 31, 2021 | May 17, 2021 | 47d | 31 | $1.8B | 13F-HR |
| Q4 2020 | Dec 31, 2020 | Feb 16, 2021 | 47d | 26 | $1.6B | 13F-HR |
| Q3 2020 | Sep 30, 2020 | Nov 16, 2020 | 47d | 22 | $1.1B | 13F-HR |
Holdings from SEC EDGAR 13F-HR filings, updated quarterly, filed up to 45 days after quarter-end. Public domain. Book totals and portfolio weights cover reported non-option positions, which can include notes and warrants. Disclosed put/call options are listed separately and excluded from those totals. Price-derived performance is withheld until the price-source policy and freshness gate are green.