X4 Pharmaceuticals, Inc SEC filings XFOR
X4 Pharmaceuticals, Inc has 818 filings in SEC EDGAR's recent list, going back to Sep 24, 2010. Its latest annual report, Form ARS, was filed on Mar 20, 2026 for the period ended Dec 31, 2025. The latest quarterly report (Form 10-Q) was filed on Nov 4, 2026, covering the quarter ended Sep 30, 2026. The most recent current report (Form 8-K) was filed on Oct 29, 2026 (other events). The company's fiscal year ends on December 31.
| Form | Description | Filed | Period |
|---|---|---|---|
| EFFECT | Filing | May 14, 2026 | — |
| CORRESP | Letter to the SEC | May 12, 2026 | — |
| UPLOAD | Letter from the SEC | May 11, 2026 | — |
| EFFECT | Filing | Sep 17, 2025 | — |
| CORRESP | Letter to the SEC | Sep 15, 2025 | — |
| UPLOAD | Letter from the SEC | Sep 15, 2025 | — |
| D | Filing | Aug 25, 2025 | — |
| UPLOAD | Letter from the SEC | Jan 7, 2025 | — |
| CORRESP | Letter to the SEC | Dec 23, 2024 | — |
| UPLOAD | Letter from the SEC | Dec 13, 2024 | — |
| EFFECT | Filing | Aug 24, 2023 | — |
| CORRESP | Letter to the SEC | Aug 22, 2023 | — |
| UPLOAD | Letter from the SEC | Aug 21, 2023 | — |
| EFFECT | Filing | Jun 20, 2023 | — |
| CORRESP | Letter to the SEC | Jun 16, 2023 | — |
| UPLOAD | Letter from the SEC | Jun 16, 2023 | — |
| D | Filing | Jun 1, 2023 | — |
| EFFECT | Filing | Aug 5, 2022 | — |
| CORRESP | Letter to the SEC | Aug 3, 2022 | — |
| UPLOAD | Letter from the SEC | Aug 2, 2022 | — |
| D | Filing | Jul 19, 2022 | — |
| EFFECT | Filing | May 13, 2022 | — |
| CORRESP | Letter to the SEC | May 12, 2022 | — |
| UPLOAD | Letter from the SEC | Apr 28, 2022 | — |
| EFFECT | Filing | Jan 3, 2022 | — |
| CORRESP | Letter to the SEC | Dec 30, 2021 | — |
| UPLOAD | Letter from the SEC | Dec 29, 2021 | — |
| EFFECT | Filing | Jul 9, 2021 | — |
| CORRESP | Letter to the SEC | Jul 7, 2021 | — |
| UPLOAD | Letter from the SEC | Jul 2, 2021 | — |
| EFFECT | Filing | Oct 26, 2020 | — |
| CORRESP | Letter to the SEC | Oct 22, 2020 | — |
| UPLOAD | Letter from the SEC | Oct 21, 2020 | — |
| EFFECT | Filing | Aug 19, 2020 | — |
| CORRESP | Letter to the SEC | Aug 17, 2020 | — |
| UPLOAD | Letter from the SEC | Aug 12, 2020 | — |
| EFFECT | Filing | Aug 29, 2019 | — |
| CORRESP | Letter to the SEC | Aug 27, 2019 | — |
| CORRESP | Letter to the SEC | Aug 22, 2019 | — |
| UPLOAD | Letter from the SEC | Aug 14, 2019 | — |
| 425 | 8-k | Mar 8, 2019 | — |
| 425 | 8-k | Mar 1, 2019 | — |
| EFFECT | Filing | Feb 19, 2019 | — |
| EFFECT | Filing | Feb 14, 2019 | — |
| CORRESP | Letter to the SEC | Feb 12, 2019 | — |
| CORRESP | Letter to the SEC | Feb 12, 2019 | — |
| UPLOAD | Letter from the SEC | Feb 8, 2019 | — |
| UPLOAD | Letter from the SEC | Feb 8, 2019 | — |
| 425 | 8-k | Dec 20, 2018 | — |
| 425 | 8-k | Nov 27, 2018 | — |
| 425 | 8-k | Nov 27, 2018 | — |
| CT ORDER | Filing | Aug 27, 2018 | — |
| D | Filing | Dec 4, 2017 | — |
| CT ORDER | Filing | Nov 16, 2017 | — |
| EFFECT | Filing | Nov 15, 2017 | — |
| CERTNAS | Auto-generated paper document | Nov 15, 2017 | — |
| 8-A12B | Form 8-a12b | Nov 15, 2017 | — |
| CORRESP | Letter to the SEC | Nov 13, 2017 | — |
| CORRESP | Letter to the SEC | Nov 13, 2017 | — |
| CORRESP | Letter to the SEC | Oct 26, 2017 | — |
| CORRESP | Letter to the SEC | Oct 20, 2017 | — |
| UPLOAD | Letter from the SEC | Oct 4, 2017 | — |
| DRSLTR | Filing | Sep 20, 2017 | — |
| DRS/A | Filing | Sep 20, 2017 | — |
| UPLOAD | Letter from the SEC | Sep 6, 2017 | — |
| DRS | Filing | Aug 10, 2017 | — |
| D | Filing | May 8, 2017 | — |
| D | Filing | Apr 27, 2016 | — |
| D | Filing | Dec 30, 2015 | — |
| D/A | Filing | Jun 5, 2015 | — |
| D/A | Filing | Aug 11, 2014 | — |
| D | Filing | Aug 13, 2013 | — |
| D | Filing | Feb 7, 2011 | — |
| D | Filing | Sep 24, 2010 | — |
Showing 74 filings. Main filings leave out insider and ownership forms such as Form 4; choose a type above to see them. Each form opens on SEC.gov. Older filings are on SEC EDGAR.
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Company profile
- Industry
- Biological Products, (No Diagnostic Substances) (SIC 2836)
- Listed as
- XFOR (Nasdaq)
- Fiscal year ends
- December 31
- Incorporated in
- DE
- Headquarters
- Boston, MA
- SEC filer status
- Non-accelerated filer, Smaller reporting company
- SEC CIK
- 1501697
- Former names
- Arsanis, Inc. (until Mar 13, 2019)
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All 182 Biological Products, (No Diagnostic Substances) companies
Source: SEC EDGAR filings. This is company-reported data, not investment advice.