Fairmount Funds Management LLC 13F: Portfolio & Holdings
Fairmount Funds Management LLC (SEC CIK 0001802528) reported 12 positions with a combined market value of $1.4 billion in its most recent SEC Form 13F-HR filing (as of Q1 2026). The West Conshohocken-based hedge fund has a Healthcare sector tilt, which represents 100.0% of its exposure.
Its largest holdings are Damora Therapeutics INC (DMRA) at 16.3%, Dianthus Therapeutics in (DNTH) at 15.4%, and Cogent Biosciences INC (COGT) at 15.3%.
The largest new position was Damora Therapeutics INC (DMRA) at 16.3% of the portfolio. See the fund’s full Q1 2026 buys, sells, and portfolio changes →
Based on published SEC 13F filings, Fairmount's closest peer funds by portfolio overlap are Avidity Partners Management LP (65.0%), Octagon Capital Advisors LP (28.1%), and Commodore Capital LP (22.9%).
- 13F AUM
- $1.4B
- Equity Positions
- 12
- Top-10 Concentration
- 97.1%
- Largest Sector · 100.0%
- Healthcare
- Longest-Held Position · 23 qtrs
- AXSM
- Median Holding Period
- 4 Qtrs
What are Fairmount’s largest 13F holdings as of Q1 2026?
Largest 13F positions disclosed by Fairmount, ranked by portfolio weight. Full multi-quarter history and the broader institutional holder base for each ticker linked per row.
| # | Issuer | Ticker | Sector | Weight | Position Value | Detail |
|---|---|---|---|---|---|---|
| 1 | DAMORA THERAPEUTICS INC NEW | DMRA | Healthcare | 16.3% | $225.7M | Position History All Holders |
| 2 | DIANTHUS THERAPEUTICS IN | DNTH | Healthcare | 15.4% | $212.9M | Position History All Holders |
| 3 | COGENT BIOSCIENCES INC | COGT | Healthcare | 15.3% | $211.8M | Position History All Holders |
| 4 | SPYRE THERAPEUTICS INC | SYRE | Healthcare | 14.6% | $202.7M | Position History All Holders |
| 5 | ORUKA THERAPEUTICS INC | ORKA | Healthcare | 13.1% | $181.7M | Position History All Holders |
| 6 | VIRIDIAN THERAPEUTICS INC | VRDN | Healthcare | 5.5% | $76.6M | Position History All Holders |
| 7 | ENLIVEN THERAPEUTICS INC | ELVN | Healthcare | 5.3% | $72.7M | Position History All Holders |
| 8 | JADE BIOSCIENCES INC | JBIO | Healthcare | 4.6% | $64.0M | Position History All Holders |
| 9 | CRESCENT BIOPHARMA INC. | CBIO | Healthcare | 3.6% | $50.5M | Position History All Holders |
| 10 | ZENAS BIOPHARMA INC | ZBIO | Healthcare | 3.3% | $46.1M | Position History All Holders |
View Fairmount's Q1 2026 portfolio changes and trading report →
Portfolio composition
Sectors, concentrations, and a tap-through treemap of every position in the fund's latest 13F.
Holding period analytics
Distribution of holding periods for all 71 stocks the fund has ever held (up to selected quarter):
Which Funds Hold a Similar Portfolio to Fairmount?
Ranked by percentage of the peer fund's 13F equity portfolio that overlaps with Fairmount's positions in Q1 2026.
| # | Fund | Shared Positions | Overlap % |
|---|---|---|---|
| 1 | Avidity Partners Management LP | 4 | 65.0% |
| 2 | Octagon Capital Advisors LP | 2 | 28.1% |
| 3 | Commodore Capital LP | 5 | 22.9% |
| 4 | Exome Asset Management LLC | 4 | 14.0% |
| 5 | Spruce Street Capital LP | 3 | 12.1% |
| 6 | Vestal Point Capital, LP | 6 | 8.8% |
| 7 | Paradigm Biocapital Advisors LP | 4 | 7.9% |
| 8 | Rtw Investments, LP | 7 | 7.9% |
| 9 | Jones Hill Capital LP | 2 | 6.5% |
| 10 | Saturn V Capital Management LP | 2 | 5.5% |
How Has Fairmount's AUM Changed Over Time?
Quarterly 13F-reported AUM for Fairmount, derived from aggregate reported position market values disclosed to the U.S. SEC.
| Quarter | 13F AUM (USD) | QoQ Change |
|---|---|---|
| Q4 2019 | $165M | — |
| Q1 2020 | $165M | +0.0B |
| Q2 2020 | $224M | +0.1B |
| Q3 2020 | $236M | +0.0B |
| Q4 2020 | $280M | +0.0B |
| Q1 2021 | $237M | -0.0B |
| Q2 2021 | $243M | +0.0B |
| Q3 2021 | $275M | +0.0B |
| Q4 2021 | $303M | +0.0B |
| Q1 2022 | $423M | +0.1B |
| Q2 2022 | $437M | +0.0B |
| Q3 2022 | $542M | +0.1B |
| Q4 2022 | $630M | +0.1B |
| Q1 2023 | $581M | -0.0B |
| Q2 2023 | $709M | +0.1B |
| Q3 2023 | $831M | +0.1B |
| Q4 2023 | $946M | +0.1B |
| Q1 2024 | $917M | -0.0B |
| Q2 2024 | $885M | -0.0B |
| Q3 2024 | $1.2B | +0.3B |
| Q4 2024 | $1.0B | -0.2B |
| Q1 2025 | $645M | -0.4B |
| Q2 2025 | $772M | +0.1B |
| Q3 2025 | $1.1B | +0.3B |
| Q4 2025 | $1.3B | +0.2B |
| Q1 2026 | $1.4B | +0.1B |
Methodology & FAQ
How We Track Fairmount Holdings
Our data is systematically aggregated directly from quarterly Form 13F-HR disclosures submitted to the U.S. Securities and Exchange Commission (SEC).
- Who Must File (Reporting Threshold): This dataset includes filings from U.S. institutional investment managers, hedge funds, mutual funds, university endowments, and family offices managing at least $100 million in Section 13(f) securities (including equities, options, convertibles, ETFs, and warrants).
- What is Included (Data Scope): By regulation, 13F filings include long positions in U.S. exchange-listed stocks, ETFs, shares of closed-end investment companies, and convertible debt, as defined in the SEC's official Section 13(f) securities list . For listed options (calls/puts) the reported value is based on the notional value.
- Portfolio Weight Explained (Metric Definition): “Portfolio Weight” shows how much of a fund's total reported 13F portfolio value (excluding listed options) is allocated to a specific position on the reporting date.
- How to Use This Data (Interpretation): Quarter-over-quarter changes in shares and portfolio weight reflect a combination of active trading and market price movements. These are descriptive metrics of fund allocation, not explicit buy or sell signals.
What does Fairmount's 13F filing disclose about their portfolio?
A Form 13F-HR filed by Fairmount with the U.S. SEC discloses all long positions in Section 13(f) securities — U.S.-listed equities, ETFs, closed-end funds, and listed put/call options — held at quarter-end with a market value of at least $200,000 or 10,000 or more shares. Pactolio aggregates these filings to surface the manager’s reported portfolio weights, share counts, and quarter-over-quarter portfolio changes in a structured format. The filing represents a point-in-time snapshot of disclosed long-side exposure, not a real-time or complete view of the fund’s total book.
How do you measure conviction in Fairmount's portfolio allocations?
Conviction is measured by portfolio weight — the percentage of Fairmount’s total reported 13F market value allocated to a given position — rather than by absolute share count or dollar value alone. A position representing a disproportionately large share of the fund’s disclosed book signals high-conviction allocation, regardless of whether it ranks among the fund’s largest absolute holdings.
What is excluded from Fairmount's 13F — short positions, swaps, and derivatives?
SEC Form 13F requires disclosure of long positions only. Specifically excluded are: short interest, total return swaps, credit default swaps, and all OTC derivatives — none of which appear in 13F filings regardless of position size. Listed put and call options must be disclosed but are excluded from portfolio weight calculations on this platform so that reported weights reflect direct equity exposure and remain comparable across filers. This means Fairmount’s 13F represents the reported long book, which may differ materially from its net economic exposure.
When is Fairmount's 13F data available, and how large is the reporting lag?
Investment managers must submit Form 13F within 45 calendar days of each quarter-end (the T+45 deadline). Pactolio ingests filings directly from SEC EDGAR as they are published — managers who file early appear in our system before the deadline, while late filers are captured on their actual filing date. The quarter label shown at the top of this page reflects the most recently processed 13F cycle for Fairmount. The inherent reporting lag means the data always reflects positions as of the prior quarter-end, not current holdings.
Who must file a Form 13F with the SEC, and does Fairmount qualify?
Under SEC Rule 13f-1, any investment manager — including hedge funds, family offices, registered investment advisers, pension funds, and university endowments — that exercises investment discretion over $100 million or more in Section 13(f) securities at any point during a calendar year must file Form 13F for that year. Fairmount meets this threshold, which is why its holdings are publicly disclosed and accessible on this platform. The $100 million threshold is evaluated on a rolling basis, meaning new filers can enter and existing filers can exit the disclosure regime as AUM crosses that boundary.