Atrium Therapeutics, Inc.: which funds bought and sold
Institutions that bought and sold Atrium Therapeutics shares in Q2 2026, from the holdings they reported to the SEC on Form 13F for March 31, 2026 and June 30, 2026.
Between March 31, 2026 and June 30, 2026, 81 institutions that filed 13F reports for both quarters added to or opened positions in Atrium Therapeutics, and 79 cut or closed them. Together they added a net 1.1M shares, +7.7% on what they held at the start of the quarter. Active managers and hedge funds on our list were net sellers of 705K shares (−11.2%); index fund managers were net buyers of 236K shares (+7.7%). 35 opened a new position and 44 sold out entirely.
Bought, Q2 2026 81 institutions, 35 of them new holders Sold, Q2 2026 79 institutions, 44 of them sold out
Net change, all compared +1.1M shares (+7.7%)
Net change, active managers −705K shares (−11.2%), 17 bought, 19 sold
Buyers versus sellers
81 bought 32 79 sold
Active managers and hedge funds 17 bought · 19 sold · −705K
Index fund managers 8 bought · 1 sold · +236K
Other institutions 56 bought · 59 sold · +1.6M
Biggest buyers
| Institution | Change in shares | Shares June 30, 2026 | Value |
|---|---|---|---|
| Crcm LP | +1.3M New position | 1.3M | $17.3M |
| Sessa Capital Im, L.P. Hedge fund | +949K +172.0% | 1.5M | $20.2M |
| Arbiter Partners Capital Management LLC | +293K +127.2% | 523K | $7M |
| Cantor Fitzgerald, L. P. | +278K +118.1% | 514K | $6.9M |
| Blackrock, Inc. Index funds | +242K +20.1% | 1.4M | $19.5M |
| AQR Capital Management LLC Hedge fund | +172K New position | 172K | $2.3M |
| Two Sigma Investments, LP Hedge fund | +167K +93.5% | 345K | $4.6M |
| Dafna Capital Management LLC | +128K New position | 128K | $1.7M |
| Anson Funds Management LP Hedge fund | +125K New position | 125K | $1.7M |
| Vanguard Capital Management LLC Index funds | +104K +16.6% | 731K | $9.8M |
| Bluecrest Capital Management Ltd Hedge fund | +100K New position | 100K | $1.3M |
| Jane Street Group, LLC | +90K +450.3% | 110K | $1.5M |
| Polar Asset Management Partners Inc. | +80K +114.3% | 150K | $2M |
| Geode Capital Management, LLC Index funds | +67K +21.0% | 387K | $5.2M |
| Credit Industriel Et Commercial | +67K +290.1% | 90K | $1.2M |
| Tudor Investment Corp Et Al Hedge fund | +58K +81.6% | 130K | $1.7M |
| Awm Investment Company, Inc. | +58K +115.0% | 108K | $1.4M |
| Franklin Resources Inc Active manager | +57K New position | 57K | $762,602 |
| Slotnik Capital, LLC | +57K +31.3% | 238K | $3.2M |
| Jacobs Levy Equity Management, Inc Active manager | +54K New position | 54K | $726,192 |
| Institution | Change in shares | Shares June 30, 2026 | Value |
|---|---|---|---|
| Sessa Capital Im, L.P. Hedge fund | +949K +172.0% | 1.5M | $20.2M |
| AQR Capital Management LLC Hedge fund | +172K New position | 172K | $2.3M |
| Two Sigma Investments, LP Hedge fund | +167K +93.5% | 345K | $4.6M |
| Anson Funds Management LP Hedge fund | +125K New position | 125K | $1.7M |
| Bluecrest Capital Management Ltd Hedge fund | +100K New position | 100K | $1.3M |
| Tudor Investment Corp Et Al Hedge fund | +58K +81.6% | 130K | $1.7M |
| Franklin Resources Inc Active manager | +57K New position | 57K | $762,602 |
| Jacobs Levy Equity Management, Inc Active manager | +54K New position | 54K | $726,192 |
| Exoduspoint Capital Management, LP Hedge fund | +40K +51.4% | 117K | $1.6M |
| Schonfeld Strategic Advisors LLC Hedge fund | +36K +22.4% | 199K | $2.7M |
Biggest sellers
| Institution | Change in shares | Shares June 30, 2026 | Value |
|---|---|---|---|
| RA Capital Management, L.P. Hedge fund | −864K Sold out | 0 | — |
| Pentwater Capital Management LP Hedge fund | −603K Sold out | 0 | — |
| Farallon Capital Management, L.L.C. Hedge fund | −349K Sold out | 0 | — |
| Bellevue Group AG | −263K Sold out | 0 | — |
| Vanguard Portfolio Management LLC Index funds | −243K −70.6% | 101K | $1.4M |
| AQR Arbitrage LLC | −180K Sold out | 0 | — |
| Balyasny Asset Management L.P. Hedge fund | −129K −55.0% | 106K | $1.4M |
| Morgan Stanley | −123K −74.6% | 42K | $564,123 |
| Squarepoint Ops LLC Hedge fund | −85K −36.6% | 147K | $2M |
| Adage Capital Partners Gp, L.L.C. Hedge fund | −84K −45.5% | 100K | $1.3M |
| Price T Rowe Associates Inc Active manager | −80K −5.2% | 1.5M | $19.8M |
| Neuberger Berman Group LLC Active manager | −69K Sold out | 0 | — |
| Quarry LP | −67K Sold out | 0 | — |
| Westchester Capital Management, LLC Hedge fund | −55K Sold out | 0 | — |
| Tig Advisors, LLC | −46K −7.6% | 562K | $7.6M |
| Marble Bar Asset Management LLP | −43K −29.4% | 104K | $1.4M |
| Citadel Advisors LLC Hedge fund | −42K −38.5% | 68K | $909,745 |
| Highbridge Capital Management LLC Hedge fund | −41K Sold out | 0 | — |
| Goldman Sachs Group Inc | −40K −11.3% | 310K | $4.2M |
| Fifth Lane Capital, LP | −36K Sold out | 0 | — |
| Institution | Change in shares | Shares June 30, 2026 | Value |
|---|---|---|---|
| RA Capital Management, L.P. Hedge fund | −864K Sold out | 0 | — |
| Pentwater Capital Management LP Hedge fund | −603K Sold out | 0 | — |
| Farallon Capital Management, L.L.C. Hedge fund | −349K Sold out | 0 | — |
| Balyasny Asset Management L.P. Hedge fund | −129K −55.0% | 106K | $1.4M |
| Squarepoint Ops LLC Hedge fund | −85K −36.6% | 147K | $2M |
| Adage Capital Partners Gp, L.L.C. Hedge fund | −84K −45.5% | 100K | $1.3M |
| Price T Rowe Associates Inc Active manager | −80K −5.2% | 1.5M | $19.8M |
| Neuberger Berman Group LLC Active manager | −69K Sold out | 0 | — |
| Westchester Capital Management, LLC Hedge fund | −55K Sold out | 0 | — |
| Citadel Advisors LLC Hedge fund | −42K −38.5% | 68K | $909,745 |
New positions
| Institution | Shares | Value June 30, 2026 |
|---|---|---|
| Crcm LP | 1.3M | $17.3M |
| AQR Capital Management LLCHedge fund | 172K | $2.3M |
| Dafna Capital Management LLC | 128K | $1.7M |
| Anson Funds Management LPHedge fund | 125K | $1.7M |
| Bluecrest Capital Management LtdHedge fund | 100K | $1.3M |
| Franklin Resources IncActive manager | 57K | $762,602 |
| Jacobs Levy Equity Management, IncActive manager | 54K | $726,192 |
| Y-Intercept (Hong Kong) Ltd | 35K | $472,135 |
| Moran Wealth Management, LLC | 33K | $448,154 |
| Los Angeles Capital Management LLCActive manager | 31K | $423,367 |
Sold out
| Institution | Shares | Value March 31, 2026 |
|---|---|---|
| RA Capital Management, L.P.Hedge fund | 864K | $11.6M |
| Pentwater Capital Management LPHedge fund | 603K | $8.1M |
| Farallon Capital Management, L.L.C.Hedge fund | 349K | $4.7M |
| Bellevue Group AG | 263K | $3.5M |
| AQR Arbitrage LLC | 180K | $2.4M |
| Neuberger Berman Group LLCActive manager | 69K | $926,460 |
| Quarry LP | 67K | $891,124 |
| Westchester Capital Management, LLCHedge fund | 55K | $738,506 |
| Highbridge Capital Management LLCHedge fund | 41K | $555,360 |
| Fifth Lane Capital, LP | 36K | $481,307 |
Who holds the shares
- Institutions reporting
- 153
- Ten largest holders
- 56.6% of 13F-reported shares
- Index fund managers
- 21.4% of 13F-reported shares
- Active managers and hedge funds
- 36.2% of 13F-reported shares
| Type | Bought | Sold | New | Sold out | Net change in shares | Net % |
|---|---|---|---|---|---|---|
| Active managers and hedge funds | 17 | 19 | 8 | 12 | −705K | −11.2% |
| Index fund managers | 8 | 1 | 0 | 0 | +236K | +7.7% |
| Other institutions | 56 | 59 | 27 | 32 | +1.6M | +33.0% |
← Back to Atrium Therapeutics, Inc. · Insiders · Politicians