RTW INVESTMENTS, LP: INSMED INC (INSM): Quarterly 13F Position History
As of Q1 2026, RTW INVESTMENTS, LP reported 4,842,880 shares of INSMED INC (INSM), worth $791.9M and representing 7.9% of its 13F equity book. Quarter-over-quarter share count change: + 1 (+0.0%) . The position first appeared in Q2 2023 and has been disclosed across 12 13F-HR filings in Pactolio's tracked window.
- 4,842,880Shares Held (Latest Filing)
- $791.9MReported Market Value (Latest Filing)
- 7.9%Portfolio Weight (% of 13F Equity Book)
- +1Quarter-over-Quarter Share Change
- -$50.9MQuarter-over-Quarter Value Change
- 4,842,880Peak Reported Shares (Historical)
Quarterly 13F-HR Disclosure History Source: SEC 13F-HR filings, 12 quarter s
| Quarter | Shares | QoQ Share Change | Share Change (%) | Market Value | Weight | Implied Price |
|---|---|---|---|---|---|---|
| Q1 2026 | 4,842,880 | +1 | +0.0% | $791.9M | 7.9% | $163.5 |
| Q4 2025 | 4,842,879 | +1,758,321 | +57.0% | $842.9M | 8.4% | $174.0 |
| Q3 2025 | 3,084,558 | 0 | — | $444.2M | 5.5% | $144.0 |
| Q2 2025 | 3,084,558 | +70,000 | +2.3% | $310.4M | 4.4% | $100.6 |
| Q1 2025 | 3,014,558 | 0 | — | $230.0M | 3.5% | $76.3 |
| Q4 2024 | 3,014,558 | 257,450 | -7.9% | $208.1M | 3.1% | $69.0 |
| Q3 2024 | 3,272,008 | 368,100 | -10.1% | $238.9M | 3.5% | $73.0 |
| Q2 2024 | 3,640,108 | +1,775,000 | +95.2% | $243.9M | 3.8% | $67.0 |
| Q1 2024 | 1,865,108 | 0 | — | $50.6M | 0.7% | $27.1 |
| Q4 2023 | 1,865,108 | 0 | — | $57.8M | 0.9% | $31.0 |
| Q3 2023 | 1,865,108 | +865,108 | +86.5% | $47.1M | 1.0% | $25.3 |
| Q2 2023 | 1,000,000 | — | — | $21.1M | 0.4% | $21.1 |
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 RTW INVESTMENTS, LP first disclose a INSM position in 13F-HR filings?
RTW INVESTMENTS, LP first reported INSMED INC (INSM) on its 13F-HR filing for the period ending 2023-06-30 (Q2 2023). The position has appeared on 12 reported quarters within Pactolio's tracked window.
What was RTW INVESTMENTS, LP's most recent quarter-over-quarter share-count change in INSM?
Between Q4 2025 and Q1 2026, RTW INVESTMENTS, LP added 1 shares of INSM (+0.0%), bringing the total reported position to 4,842,880 shares at a market value of $791.9M.
Does the implied price-per-share represent RTW INVESTMENTS, LP's cost basis in INSM?
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.