X4 PHARMACEUTICALS INC XFOR
COM NEW · Common Stock · CUSIP 98420X202
- SectorHealth care
- IndustryBiological Products, (No Diagnostic Substances)
- HeadquartersBoston, MA
- FilingsSEC EDGAR
* Summed across managers. Shares that two managers' reports both contain – a subsidiary's holdings that its parent's report includes too, or a sub-adviser's in its client's – are counted once. Holder counts are more reliable. Shares outstanding: 99.1m as of 2026-07-31, from the company's own SEC filing; the percentage can still exceed 100%: lent-out shares are counted by the lender and the buyer, and some reports overlap without saying so. Implied quarter-end price ≈ $4.67. Options: 2 managers hold calls ($2.3m notional), 0 hold puts (—).
Trends to Q2 2026
Institutional holders
Managers reporting a position, each quarter
Numbers
| Quarter | Holders |
|---|---|
| Q1 2025 | 2 |
| Q2 2025 | 51 |
| Q3 2025 | 40 |
| Q4 2025 | 76 |
| Q1 2026 | 82 |
| Q2 2026 | 88 |
Buyers vs sellers
Managers adding to or starting a position, vs cutting or selling out
Numbers
| Quarter | Bought or added | Cut or sold out |
|---|---|---|
| Q2 2025 | 49 | 2 |
| Q3 2025 | 21 | 30 |
| Q4 2025 | 51 | 12 |
| Q1 2026 | 39 | 31 |
| Q2 2026 | 57 | 39 |
Calls vs puts
Options held, notional value, last 4 quarters. P/C = puts ÷ calls
Numbers
| Quarter | Calls | Puts | P/C |
|---|---|---|---|
| Q3 2025 | $1.1m | $72.8k | 0.07 |
| Q4 2025 | $1.2m | $0 | 0.00 |
| Q1 2026 | $0 | $0 | — |
| Q2 2026 | $2.3m | $0 | 0.00 |
Biggest buyers
| BlackRock, Inc. | Added | +4.3m |
| Nantahala Capital Management, LLC | Added | +2.4m |
| Venrock Adviser, LLC | Added | +1.6m |
| PERCEPTIVE ADVISORS LLC | Added | +1.2m |
| GEODE CAPITAL MANAGEMENT, LLC | Added | +1.2m |
| STATE STREET CORP | Added | +892.5k |
| VANGUARD PORTFOLIO MANAGEMENT LLC | New | +542.1k |
| Saturn V Capital Management LP | Added | +516.7k |
| NORTHERN TRUST CORP | Added | +474.6k |
| Verdad Advisers, LP | New | +352.1k |
Biggest sellers
| Empery Asset Management, LP | Reduced | -2.0m |
| STEMPOINT CAPITAL LP | Sold out | -1.7m |
| MILLENNIUM MANAGEMENT LLC | Sold out | -1.2m |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | Reduced | -842.2k |
| Deep Track Capital, LP | Reduced | -460.8k |
| SAMSARA BIOCAPITAL, LLC | Reduced | -437.0k |
| BRAIDWELL LP | Reduced | -350.2k |
| MARSHALL WACE, LLP | Sold out | -336.8k |
| Qube Research & Technologies Ltd | Sold out | -219.0k |
| UBS Group AG | Reduced | -209.3k |
Biggest calls
| SUSQUEHANNA INTERNATIONAL GROUP, LLP | New | $1.2m250.3k shares |
| Caption Management, LLC | New | $1.2m250.0k shares |
Biggest puts
| None |
Options at notional value: the value of the shares the contracts control, as filers report them, not what the options cost. Not included in the holders, shares or buying above.
Major shareholders (over 5%)
Anyone who owns more than 5% of a class of the company's shares has to say so: on Schedule 13D if they may try to influence or control the company, on 13G if they're a passive investor, and update it as the stake changes. Each holder's latest filing, from 19 Dec 2024 on; percentages are of the share class, as the holder worked them out.
| Holder | Stake |
|---|---|
| MORGAN STANLEY 13G · institution +0.8 pts · filed 2026-03-06 | 10.2% |
| Empery Asset Management, LP 13G · institution no change · filed 2026-01-15 | 10.0% |
| Coastlands Capital LP 13G · institution no change · filed 2025-10-03 | 10.0% |
| Deep Track Capital, LP 13G · passive investor -1.7 pts · filed 2026-08-14 | 8.3% |
| PERCEPTIVE ADVISORS LLC 13G · passive investor +0.8 pts · filed 2026-08-14 | 8.1% |
| Bain Capital Life Sciences Fund, L.P. 13G · passive investor -2.6 pts · filed 2026-02-17 | 7.4% |
| Saturn V Capital Management LP 13G · institution new · filed 2026-02-17 | 7.4% |
Growth Equity Opportunities 18 VGE, LLC
13D · may seek influence
-3.8 pts · filed 2025-10-29
Stated purposeGEO acquired the GEO Shares for investment purposes. Information with respect to the Offering set forth in Item 3 above is incorporated herein by reference to the extent responsive to this Item 4. Subject to the foregoing, depending on market conditions, its continuing evaluation of the business and prospects of the Issuer and other factors, GEO and other Reporting Persons may dispose of or acquire additional shares of the Issuer. Except as set forth above, none of the Reporting Persons has any present plans which relate to or would result in: (a) The acquisition by any person of additional securities of the Issuer, or the disposition of securities of the Issuer; (b) An extraordinary corporate transaction, such as a merger, reorganization or liquidation, involving the Issuer or any of i… Full filing |
6.2% |
| BlackRock, Inc. 13G · institution +2.9 pts · filed 2026-07-30 | 5.9% |
| Trails Edge Capital Partners, LP 13G · passive investor -4.1 pts · filed 2026-02-17 | 5.8% |
| Venrock Healthcare Capital Partners III, L.P. 13G · passive investor new · filed 2026-09-21 | 5.6% |
Fell to 5% or below in the last year: FMR LLC (4.6%, 2026-10-07), BIOTECHNOLOGY VALUE FUND L P (3.9%, 2026-02-17), Nantahala Capital Management, LLC (2.8%, 2026-02-13)
Insider purchases and sales since 1 Apr 2026
Shares bought or sold by the company's own officers, directors and 10% owners, in the open market or privately, as they reported to the SEC on Form 4 (due within two business days of the trade). Grants, option exercises, shares withheld for tax and gifts aren't included.
Officers and directors buying vs selling
Number of people, by quarter (10% owners not included)
Numbers
| Quarter | Buying | Bought | Selling | Sold | Sold under a plan |
|---|---|---|---|---|---|
| Q4 2024 | 1 | $4.6k | 5 | $377.0k | — |
| Q1 2025 | 0 | — | 5 | $96.4k | — |
| Q2 2025 | 0 | — | 0 | — | — |
| Q3 2025 | 0 | — | 0 | — | — |
| Q4 2025 | 1 | $250.0k | 0 | — | — |
| Q1 2026 | 0 | — | 0 | — | — |
| Q2 2026 | 0 | — | 1 | $109.2k | — |
| Q3 2026 | 0 | — | 2 | $319.7k | — |
| Date | Insider | Trade | Value |
|---|---|---|---|
| 2026-08-12 | Craig Adam R Executive Chairman, director | Sold | $210.6k47.4k shares |
| 2026-08-12 | Volpone John President | Sold | $109.1k24.6k shares |
| 2026-06-30 | KIRSKE DAVID Chief Financial Officer | Sold | $36.4k8.5k shares |
| 2026-05-12 | KIRSKE DAVID Chief Financial Officer | Sold | $72.8k17.0k shares |
Their holding: how much the trade added to or took from the insider's holding (direct, or the trust or fund named). The same trade is sometimes reported by more than one insider, such as a fund and the director who represents it; totals count it once. A value is left blank where the reported price is far from the market price (usually a typo).
Holders, Q2 2026
| Manager | Shares | Change |
|---|---|---|
| MORGAN STANLEY 0.00% of their portfolio | 9.5m $44.2m | Reduced -5.7k |
| FMR LLC 0.00% of their portfolio | 8.3m $38.9m | Added +218.3k |
| Bain Capital Life Sciences Investors, LLC 2.21% of their portfolio | 8.0m $37.2m | Unchanged |
| PERCEPTIVE ADVISORS LLC 0.58% of their portfolio | 7.9m $37.0m | Added +1.2m |
| Kalehua Capital Management LLC 11.09% of their portfolio | 7.4m $34.8m | Unchanged |
| Saturn V Capital Management LP 4.67% of their portfolio | 7.0m $32.6m | Added +516.7k |
| Empery Asset Management, LP 37.43% of their portfolio | 6.9m $32.4m | Reduced -2.0m |
| Deep Track Capital, LP 0.40% of their portfolio | 5.9m $27.5m | Reduced -460.8k |
| BlackRock, Inc. 0.00% of their portfolio | 5.6m $25.9m | Added +4.3m |
| Nantahala Capital Management, LLC 0.69% of their portfolio | 4.9m $22.9m | Added +2.4m |
| VANGUARD CAPITAL MANAGEMENT LLC 0.00% of their portfolio | 3.7m $17.4m | Added +218.2k |
| Rosalind Advisors, Inc. 5.64% of their portfolio | 3.2m $15.0m | Unchanged |
| BRAIDWELL LP 0.50% of their portfolio | 2.9m $13.6m | Reduced -350.2k |
| Blackstone Inc. 0.04% of their portfolio | 2.7m $12.5m | Unchanged |
| Trails Edge Capital Partners, LP 1.91% of their portfolio | 2.6m $12.0m | Unchanged |
| BVF INC/IL 0.27% of their portfolio | 2.2m $10.4m | Unchanged |
| GEODE CAPITAL MANAGEMENT, LLC 0.00% of their portfolio | 2.1m $9.8m | Added +1.2m |
| Venrock Adviser, LLC 0.27% of their portfolio | 1.9m $9.0m | Added +1.6m |
| SAMSARA BIOCAPITAL, LLC 0.54% of their portfolio | 1.4m $6.5m | Reduced -437.0k |
| STATE STREET CORP 0.00% of their portfolio | 1.3m $6.1m | Added +892.5k |
| Woodline Partners LP 0.01% of their portfolio | 1.0m $4.7m | Unchanged |
| GOLDMAN SACHS GROUP INC 0.00% of their portfolio | 916.5k $4.3m | Added +34.4k |
| NORTHERN TRUST CORP 0.00% of their portfolio | 652.8k $3.0m | Added +474.6k |
| VANGUARD FIDUCIARY TRUST CO 0.00% of their portfolio | 572.0k $2.7m | Added +91.3k |
| VANGUARD PORTFOLIO MANAGEMENT LLC 0.00% of their portfolio | 542.1k $2.5m | New |
| Verdad Advisers, LP 1.57% of their portfolio | 352.1k $1.6m | New |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC 0.00% of their portfolio | 263.3k $1.2m | Added +196.5k |
| Stonepine Capital Management, LLC 0.80% of their portfolio | 225.0k $1.1m | Reduced -110.3k |
| Bank of New York Mellon Corp 0.00% of their portfolio | 196.3k $916.9k | New |
| Affinity Asset Advisors, LLC 0.03% of their portfolio | 145.0k $677.1k | Unchanged |
| Nuveen, LLC 0.00% of their portfolio | 107.4k $501.5k | New |
| Invesco Ltd. 0.00% of their portfolio | 96.8k $451.9k | Added +76.8k |
| ALPS ADVISORS INC 0.00% of their portfolio | 95.7k $447.0k | New |
| RHUMBLINE ADVISERS 0.00% of their portfolio | 95.1k $444.0k | New |
| Susquehanna Portfolio Strategies, LLC 0.01% of their portfolio | 87.3k $407.6k | Reduced -15.3k |
| DEUTSCHE BANK AG\ 0.00% of their portfolio | 78.9k $368.4k | New |
| GSA CAPITAL PARTNERS LLP 0.02% of their portfolio | 76.3k $356.0k | New |
| AMERICAN CENTURY COMPANIES INC 0.00% of their portfolio | 74.8k $349.3k | New |
| CITIGROUP INC 0.00% of their portfolio | 70.1k $327.4k | Added +34.3k |
| WELLS FARGO & COMPANY/MN 0.00% of their portfolio | 67.7k $316.2k | New |
| Palumbo Wealth Management LLC 0.07% of their portfolio | 67.1k $313.4k | Reduced -63.9k |
| Squarepoint Ops LLC 0.00% of their portfolio | 67.1k $313.3k | New |
| PRICE T ROWE ASSOCIATES INC /MD/ 0.00% of their portfolio | 66.4k $310.0k | New |
| UBS Group AG 0.00% of their portfolio | 58.0k $271.1k | Reduced -209.3k |
| WELLINGTON MANAGEMENT GROUP LLP 0.00% of their portfolio | 51.8k $241.9k | New |
| MetLife Investment Management, LLC 0.00% of their portfolio | 48.0k $224.0k | New |
| BANK OF AMERICA CORP /DE/ 0.00% of their portfolio | 46.9k $218.8k | Reduced -103.8k |
| Point72 Asset Management, L.P. 0.00% of their portfolio | 41.1k $191.8k | New |
| MIRAE ASSET GLOBAL ETFS HOLDINGS Ltd. 0.00% of their portfolio | 37.1k $173.1k | New |
| Jump Financial, LLC 0.00% of their portfolio | 34.3k $160.0k | Added +21.9k |
| JPMORGAN CHASE & CO 0.00% of their portfolio | 33.6k $141.9k | Added +33.5k |
| Vanguard Global Advisers, LLC 0.00% of their portfolio | 33.0k $154.0k | Unchanged |
| Police & Firemen's Retirement System of New Jersey 0.00% of their portfolio | 23.8k $111.4k | New |
| AXQ CAPITAL, LP 0.01% of their portfolio | 22.9k $106.8k | New |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE 0.00% of their portfolio | 22.1k $103.1k | New |
| BARCLAYS PLC 0.00% of their portfolio | 19.4k $90.8k | Added +16.6k |
| TWO SIGMA INVESTMENTS, LP 0.00% of their portfolio | 19.4k $90.7k | Added +5.6k |
| STIFEL FINANCIAL CORP 0.00% of their portfolio | 18.5k $86.5k | Reduced -3.3k |
| RENAISSANCE TECHNOLOGIES LLC 0.00% of their portfolio | 18.1k $84.5k | New |
| INTECH INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 17.3k $80.7k | New |
| NEW YORK STATE COMMON RETIREMENT FUND 0.00% of their portfolio | 16.5k $77.1k | New |
| BNP PARIBAS FINANCIAL MARKETS 0.00% of their portfolio | 16.4k $76.5k | Added +11.6k |
| VOYA INVESTMENT MANAGEMENT LLC 0.00% of their portfolio | 15.8k $74.0k | New |
| CAXTON CORP 3.92% of their portfolio | 15.6k $72.7k | Unchanged |
| ALLIANCEBERNSTEIN L.P. 0.00% of their portfolio | 14.6k $60.2k | New |
| WINTON GROUP Ltd 0.00% of their portfolio | 14.4k $67.2k | Added +3.8k |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP 0.00% of their portfolio | 14.1k $65.6k | Reduced -842.2k |
| Creative Planning 0.00% of their portfolio | 13.9k $64.8k | Added +53 |
| PRUDENTIAL FINANCIAL INC 0.00% of their portfolio | 12.5k $58.4k | New |
| ProShare Advisors LLC 0.00% of their portfolio | 10.6k $49.4k | New |
| Pettinga Financial Advisors LLC 0.01% of their portfolio | 10.0k $46.7k | New |
| Indivisible Partners 0.00% of their portfolio | 10.0k $46.9k | Unchanged |
| Legal & General Group Plc 0.00% of their portfolio | 7.9k $36.7k | New |
| Tower Research Capital LLC (TRC) 0.00% of their portfolio | 7.7k $36.2k | Added +7.6k |
| Ameritas Investment Partners, Inc. 0.00% of their portfolio | 7.3k $34.3k | New |
| Russell Investments Group, Ltd. 0.00% of their portfolio | 7.2k $33.5k | Added +6.4k |
| ROYAL BANK OF CANADA 0.00% of their portfolio | 2.6k $12.0k | Added +2.4k |
| PNC Financial Services Group, Inc. 0.00% of their portfolio | 1.8k $8.2k | Unchanged |
| Sterling Capital Management LLC 0.00% of their portfolio | 1.6k $7.6k | New |
| CALIFORNIA STATE TEACHERS RETIREMENT SYSTEM 0.00% of their portfolio | 1.1k $5.2k | New |
| GROUP ONE TRADING LLC 0.00% of their portfolio | 712 $3.3k | Unchanged |
| Bleichroeder LP 0.00% of their portfolio | 595 $2.8k | Unchanged |
| Blue Trust, Inc. 0.00% of their portfolio | 284 $1.3k | Unchanged |
| JONES FINANCIAL COMPANIES LLLP 0.00% of their portfolio | 38 $153 | Unchanged |
| Rockefeller Capital Management L.P. 0.00% of their portfolio | 33 $154 | Unchanged |
| Caitong International Asset Management Co., Ltd 0.00% of their portfolio | 30 $140 | New |
| SBI Securities Co., Ltd. 0.00% of their portfolio | 9 $42 | Reduced -45 |
| HighMark Wealth Management LLC 0.00% of their portfolio | 6 $28 | Unchanged |