X4 Pharmaceuticals, Inc.
X4 Pharmaceuticals, Inc. (XFOR) Stock Ownership
Institutional vs insider vs public ownership from 13F and float data — top holders, activity, and insider trades below.
SEC 13F · FMP · XFOR · as of Sep 30, 2025
Ownership Breakdown
41
Institutional Holders
▼ 11 vs Q2
$46.69M
Total Inst. Value
▲ $41.36M vs Q2
94.32M
Shares Outstanding
freeFloat 60.87%
13.65M
13F Shares Held
▲ 10.85M vs Q2
Institutional ownership = 13F shares ÷ total outstanding. Insider % = 100 − free float. Public % = free float − institution %. Data: FMP /symbol-positions-summary + /shares-float + SEC EDGAR.
Top Institutional Holders
XFOR largest shareholders · institutional ownership
Q3 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
BAIN CAPITAL LIFE SCIENCES INVESTORS, LLC biological products, (no diagnostic substances) | 2.44M | 32.87% | 32.87% | $8.33B | Nov 14, 2025 | ▲ 1.87M |
BVF INC/IL biological products, (no diagnostic substances) | 2.23M | 30.13% | 30.13% | $7.64B | Nov 14, 2025 | NEW |
NANTAHALA CAPITAL MANAGEMENT, LLC biological products, (no diagnostic substances) | 2.23M | 30.06% | 30.06% | $7.62B | Nov 14, 2025 | NEW |
ROSALIND ADVISORS, INC. biological products, (no diagnostic substances) | 1.54M | 20.84% | 20.84% | $5.28B | Nov 13, 2025 | NEW |
DEEP TRACK CAPITAL, LP biological products, (no diagnostic substances) | 1.12M | 15.14% | 15.14% | $3.84B | Nov 14, 2025 | NEW |
STONEPINE CAPITAL MANAGEMENT, LLC biological products, (no diagnostic substances) | 1.06M | 14.25% | 14.25% | $3.61B | Nov 13, 2025 | NEW |
KINGDON CAPITAL MANAGEMENT, L.L.C. biological products, (no diagnostic substances) | 933.3K | 12.59% | 12.59% | $3.19B | Nov 14, 2025 | ▲ 700.0K |
STEMPOINT CAPITAL LP biological products, (no diagnostic substances) | 555.4K | 7.49% | 7.49% | $1.90B | Nov 14, 2025 | NEW |
VANGUARD GROUP INC biological products, (no diagnostic substances) | 410.5K | 5.54% | 5.54% | $1.40B | Nov 7, 2025 | ▲ 178.6K |
BOOTHBAY FUND MANAGEMENT, LLC biological products, (no diagnostic substances) | 344.0K | 4.64% | 4.64% | $1.18B | Nov 14, 2025 | NEW |
Data from SEC Form 13F filings. Ownership bar normalised to largest holder. Change flags: isNew / isSoldOut / changeInSharesNumber (FMP extract-analytics/holder).
Institutional Activity
Q3 2025 vs prior quarter
Q3 2025
9
Increased
+2.98M shares11
New Positions
first time holders10
Decreased
−209.2K shares9
Sold Out
fully exitedNet shares change (top 50)
+2.77M
+2.98M / −209.2K
Net new holders
+1
11 new / 9 exited
Based on top 50 institutional holders by position size. Fields: isNew, isSoldOut, changeInSharesNumber (FMP extract-analytics/holder, limit=50).
Insider Buying vs Selling
XFOR insider trading · insider activity
Source: SEC Form 4
Insiders have been net buyers of shares recently. Selling may be driven by pre-scheduled Rule 10b5-1 plans rather than negative sentiment.
0
Buy transactions
1
Sell transactions
0.00
Buy/Sell ratio
$0M
Total disposed
Recent Insider Transactions
Showing 10 most recent · Common Stock only
| Name · Role | Date | Type | Shares | Price | Value | After Trans. | Filing |
|---|---|---|---|---|---|---|---|
KIRSKE DAVID Chief Financial Officer | May 12, 2026 | Sale | 16,961 | $4.29 | $72.8K | 176.3K | Form 4 ↗ |
Bridger Gary director | Jan 1, 2026 | Award | 110,000 | $4.00 | $440.0K | 0 | Form 4 ↗ |
de Craecker Francoise director | Jan 1, 2026 | Award | 110,000 | $4.00 | $440.0K | 0 | Form 4 ↗ |
WYZGA MICHAEL S director | Jan 1, 2026 | Award | 110,000 | $4.00 | $440.0K | 0 | Form 4 ↗ |
Stewart Murray director | Jan 1, 2026 | Award | 110,000 | $4.00 | $440.0K | 0 | Form 4 ↗ |
Craig Adam R Executive Chairman | Oct 29, 2025 | Award | 2,329,154 | $1.42 | $3.31M | 2.33M | Form 4 ↗ |
Volpone John President | Oct 29, 2025 | Award | 2,329,154 | $1.42 | $3.31M | 2.33M | Form 4 ↗ |
KIRSKE DAVID Chief Financial Officer | Oct 29, 2025 | Award | 1,552,769 | $1.42 | $2.20M | 1.55M | Form 4 ↗ |
Craig Adam R Executive Chairman | Oct 23, 2025 | Purchase | 86,206 | $2.90 | $250.0K | 376.1K | Form 4 ↗ |
Volpone John President | Aug 12, 2025 | Award | 1,609,873 | $1.42 | $2.29M | 1.61M | Form 4 ↗ |
Source: /insider-trading/search (FMP stable). Buy/Sell direction: acquisitionOrDisposition A=Buy, D=Sell. RSU vesting (M-Exempt) excluded from sentiment bar. All data from SEC EDGAR public filings.
About institutional & insider ownership
X4 Pharmaceuticals, Inc. (XFOR) is primarily owned by institutional investors, who hold approximately 14.5% of total shares outstanding. Company insiders own approximately 39.13%, while retail and public investors account for the remaining 46.39%.
The largest institutional shareholder of X4 Pharmaceuticals, Inc. is BAIN CAPITAL LIFE SCIENCES INVESTORS, LLC, holding approximately 2.44 million shares — equal to 32.87% of outstanding shares — as of September 30, 2025.
A total of 41 institutional investors currently hold XFOR stock, with a combined institutional value of approximately $46,691,414 as of the most recent 13F filing period.
Frequently asked questions
XFOR ownershipX4 Pharmaceuticals, Inc. (XFOR) is primarily owned by institutional investors, who hold approximately 14.5% of shares. The largest shareholder is BAIN CAPITAL LIFE SCIENCES INVESTORS, LLC with a 32.87% stake. Company insiders hold 39.13%. Data sourced from SEC Form 13F as of September 30, 2025.