RTW Investments, LP holds a focused book of 88 stocks worth $10.0B as of Q1 2026 (disclosed May 15, 2026, a ~45-day 13F lag). This quarter they opened Waystar Holding Corp and trimmed Natera Inc. Their largest long position is Madrigal Pharmaceuticals Inc at 10% of the equity book.
The public view is the crawlable proof. The same sourced dataset is available through REST and MCP for agents, research scripts, and back-office tools.
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/1493215/holdings"
Use Arkolith to show RTW INVESTMENTS, LP's latest holdings, largest changes, and filing provenance.
Top-heavy: focused book
Share of the disclosed book in its largest positions. A higher top-5 share means a more concentrated, higher-conviction portfolio.
99% 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, no cost basis
Bars show each stock's share of the portfolio. Click a row for its position history.
| # | Security | Value | Shares | % Port | Last move | History |
|---|---|---|---|---|---|---|
| 1 | Madrigal Pharmaceuticals Inc COM | $1.0B | 1.99M | 10.4% | —Held | |
| 2 | Insmed Inc COM PAR $.01 | $791.9M | 4.84M | 7.9% | ▲~0% Added · +1 sh | |
| 3 | Protagonist Therapeutics Inc COM | $533.2M | 5.06M | 5.3% | —Held | |
| 4 | PTC Therapeutics Inc COM | $527.8M | 7.75M | 5.3% | —Held | |
| 5 | Argenx SE SPONSORED ADR | $518.1M | 709.4K | 5.2% | ▲+5.3% Added · +36K sh | |
| 6 | CG Oncology Inc COM | $472.7M | 6.98M | 4.7% | ▲+247% Added · +5.0M sh | |
| 7 | Celcuity Inc COM | $346.9M | 3.04M | 3.5% | ▲+452% Added · +2.5M sh | |
| 8 | Tango Therapeutics Inc COM | $278.2M | 13.30M | 2.8% | ▲+792% Added · +11.8M sh | |
| 9 | Erasca Inc COM | $261.4M | 16.16M | 2.6% | ▲110× Added · +16.0M sh | |
| 10 | Natera Inc COM | $250.0M | 1.25M | 2.5% | ▼−17% Reduced · −250K sh | |
| 11 | Radnet Inc COM | $239.5M | 4.29M | 2.4% | ▲+8.8% Added · +347K sh | |
| 12 | Tarsus Pharmaceuticals Inc COM | $234.7M | 3.35M | 2.3% | ▲+0.3% Added · +11K sh | |
| 13 | Apogee Therapeutics Inc COM | $234.2M | 2.78M | 2.3% | ▲+2.6% Added · +70K sh | |
| 14 | Spyre Therapeutics Inc COM NEW | $210.4M | 4.17M | 2.1% | —Held | |
| 15 | Cogent Biosciences Inc COM | $210.1M | 5.46M | 2.1% | ▼−28% Reduced · −2.1M sh | |
| 16 | Irhythm Holdings Inc COM | $196.9M | 1.67M | 2.0% | ▲+41% Added · +487K sh | |
| 17 | Stoke Therapeutics Inc COM | $183.1M | 5.62M | 1.8% | ▲+1.4% Added · +77K sh | |
| 18 | Cytokinetics Inc COM NEW | $179.4M | 2.72M | 1.8% | —Held | |
| 19 | Acadia Pharmaceuticals Inc COM | $159.0M | 7.14M | 1.6% | —Held | |
| 20 | Establishment Labs Hldgs Inc COM | $150.8M | 2.66M | 1.5% | ▲+2.6% Added · +67K sh | |
| 21 | Apellis Pharmaceuticals Inc COM | $148.2M | 3.69M | 1.5% | ▼−52% Reduced · −4.0M sh | |
| 22 | Immunocore Hldgs PLC ADS | $146.8M | 4.87M | 1.5% | —Held | |
| 23 | Repligen Corp COM | $142.1M | 1.21M | 1.4% | ▲+13% Added · +142K sh | |
| 24 | Neurocrine Biosciences Inc COM | $139.9M | 1.06M | 1.4% | —Held | |
| 25 | Guardant Health Inc COM | $136.8M | 1.48M | 1.4% | —Held | |
| 26 | Immatics N.V SHS | $126.6M | 12.87M | 1.3% | ▲+13% Added · +1.4M sh | |
| 27 | Zai Lab Ltd ADR | $123.7M | 6.57M | 1.2% | ▼−5.5% Reduced · −385K sh | |
| 28 | Belite Bio Inc SPONSORED ADS | $114.1M | 715.3K | 1.1% | —Held | |
| 29 | Intuitive Surgical Inc COM NEW | $101.4M | 220.0K | 1.0% | ▲+117% Added · +119K sh | |
| 30 | Oruka Therapeutics Inc COM | $101.0M | 2.06M | 1.0% | —Held | |
| 31 | GH Research PLC ORDINARY SHARES | $83.4M | 5.93M | 0.8% | —Held | |
| 32 | Xencor Inc COM | $81.7M | 6.78M | 0.8% | —Held | |
| 33 | Urogen Pharma Ltd COM | $81.7M | 4.54M | 0.8% | —Held | |
| 34 | Centessa Pharmaceuticals PLC SPONSORED ADS | $81.6M | 2.05M | 0.8% | ▲+15% Added · +263K sh | |
| 35 | Immunovant Inc COM | $78.9M | 3.18M | 0.8% | ▼~0% Reduced · −1 sh | |
| 36 | Ultragenyx Pharmaceutical In COM | $76.4M | 3.65M | 0.8% | ▲+22% Added · +649K sh | |
| 37 | Hinge Health Inc CL A | $74.4M | 1.93M | 0.7% | ▲+446% Added · +1.6M sh | |
| 38 | Castle Biosciences Inc COM | $67.7M | 2.76M | 0.7% | ▲+30% Added · +643K sh | |
| 39 | Rocket Pharmaceuticals Inc COM | $63.3M | 17.69M | 0.6% | —Held | |
| 40 | Taysha Gene Therapies Inc COM SHS | $61.2M | 13.68M | 0.6% | ▼−17% Reduced · −2.7M sh | |
| 41 | Alkermes PLC SHS | $59.1M | 1.67M | 0.6% | —Held | |
| 42 | Compass Pathways PLC SPONSORED ADS | $58.8M | 10.63M | 0.6% | ▲+21% Added · +1.9M sh | |
| 43 | Kodiak Sciences Inc COM | $56.7M | 1.49M | 0.6% | ▲~0% Added · +1 sh | |
| 44 | Replimune Group Inc COM | $56.3M | 7.36M | 0.6% | ▲+3.0% Added · +217K sh | |
| 45 | Crinetics Pharmaceuticals In COM | $52.7M | 1.45M | 0.5% | ▲+7.4% Added · +100K sh | |
| 46 | Uniqure NV SHS | $42.3M | 2.59M | 0.4% | ▼−30% Reduced · −1.1M sh | |
| 47 | Waystar Hldg Corp COM | $39.3M | 1.63M | 0.4% | ▲New New position | |
| 48 | Arrowhead Pharmaceuticals In COM | $36.7M | 585.7K | 0.4% | ▲+0.2% Added · +966 sh | |
| 49 | Orchestra Biomed Hldgs Inc COM | $35.3M | 8.31M | 0.4% | —Held | |
| 50 | Verastem Inc COM NEW | $34.9M | 6.58M | 0.3% | —Held |
As-of date vs the date the SEC received each filing
| Quarter | As of | Filed | Positions | Value | Form |
|---|---|---|---|---|---|
| Q1 2026 | Mar 31, 2026 | May 15, 2026 | 88 | $10.0B | 13F-HR |
| Q4 2025 | Dec 31, 2025 | Feb 17, 2026 | 91 | $10.0B | 13F-HR |
| Q3 2025 | Sep 30, 2025 | Nov 14, 2025 | 74 | $8.1B | 13F-HR |
| Q2 2025 | Jun 30, 2025 | Aug 14, 2025 | 73 | $7.0B | 13F-HR |
| Q1 2025 | Mar 31, 2025 | May 15, 2025 | 68 | $6.5B | 13F-HR |
| Q4 2024 | Dec 31, 2024 | Feb 14, 2025 | 72 | $6.6B | 13F-HR |
| Q3 2024 | Sep 30, 2024 | Nov 14, 2024 | 68 | $6.9B | 13F-HR |
| Q2 2024 | Jun 30, 2024 | Aug 14, 2024 | 68 | $6.5B | 13F-HR |
| Q1 2024 | Mar 31, 2024 | May 15, 2024 | 69 | $6.8B | 13F-HR |
| Q4 2023 | Dec 31, 2023 | Feb 14, 2024 | 64 | $6.4B | 13F-HR |
| Q3 2023 | Sep 30, 2023 | Nov 14, 2023 | 67 | $4.7B | 13F-HR |
| Q2 2023 | Jun 30, 2023 | Aug 14, 2023 | 62 | $5.3B | 13F-HR |
| Q1 2023 | Mar 31, 2023 | May 15, 2023 | 60 | $4.8B | 13F-HR |
| Q4 2022 | Dec 31, 2022 | Feb 14, 2023 | 77 | $4.9B | 13F-HR |
| Q3 2022 | Sep 30, 2022 | Nov 14, 2022 | 86 | $4.3B | 13F-HR |
| Q2 2022 | Jun 30, 2022 | Aug 15, 2022 | 107 | $3.9B | 13F-HR |
| Q1 2022 | Mar 31, 2022 | May 16, 2022 | 106 | $4.8B | 13F-HR |
| Q4 2021 | Dec 31, 2021 | Feb 14, 2022 | 124 | $6.8B | 13F-HR |
| Q3 2021 | Sep 30, 2021 | Nov 15, 2021 | 120 | $6.6B | 13F-HR |
| Q2 2021 | Jun 30, 2021 | Aug 13, 2021 | 113 | $6.6B | 13F-HR |
| Q1 2021 | Mar 31, 2021 | May 14, 2021 | 111 | $6.4B | 13F-HR |
| Q4 2020 | Dec 31, 2020 | Feb 16, 2021 | 102 | $6.0B | 13F-HR |
| Q3 2020 | Sep 30, 2020 | Nov 16, 2020 | 90 | $4.2B | 13F-HR |
| Q2 2020 | Jun 30, 2020 | Aug 14, 2020 | 77 | $3.6B | 13F-HR |
Holdings from SEC EDGAR 13F-HR filings, updated quarterly ~45 days after quarter-end. Public domain. The book and weighting are long equity only; 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.