shall be deemed to be furnished, and not filed: Exhibit No. Description 99.1 Press release dated August 6, 2026 entitled “Voyager Reports Second Quarter 2026 Financial and Operating Results”. 104 Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). 2 SIGNATURES Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized. Date: August 6…

Other Events. On July 13, 2026, Voyager Therapeutics, Inc. (the “Company”) presented good laboratory practice (“GLP”) toxicology data for VY1706, the Company’s investigational tau silencing gene therapy developed to target intracellular and extracellular tau for Alzheimer’s disease (“AD”), at the Alzheimer’s Association International Conference. The three- and six-month GLP toxicology data presented demonstrated a favorable tolerability profile for VY1706 in non-human primates (“NHPs”) in the…

Other Events. On June 1, 2026, Voyager Therapeutics, Inc. (the “Company”) announced that the U.S. Food and Drug Administration has cleared its Investigational New Drug application for VY1706, the Company’s investigational tau silencing gene therapy developed to target intracellular and extracellular tau for Alzheimer’s disease (“AD”). The Company plans to initiate a multi-site, open-label, dose-escalation clinical trial of VY1706, which is expected to begin dosing in the second half of 2026.…

shall be deemed to be furnished, and not filed: ​ ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press release dated May 7, 2026 entitled “Voyager Reports First Quarter 2026 Financial and Operating Results”. 104 ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). ​ ​ ​ ​ ​ 2 SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto dul…

Chief Financial Officer — Nathan Jorgensen, Ph.D.: Dr. Nathan Jorgensen resigned as Chief Financial Officer to pursue a new opportunity.

shall be deemed to be furnished, and not filed: ​ ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press release dated March 9, 2026 entitled “Voyager Reports Fourth Quarter and Full Year 2025 Financial and Operating Results”. 104 ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). ​ ​ ​ ​ ​ 2 SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersi…

Chief Medical Officer — Toby Ferguson, M.D., Ph.D.: Resigned to pursue a new opportunity.

of this Current Report on Form 8-K, including Exhibit 99.1 and Exhibit 99.2 hereto, the Company is not making an admission as to the materiality of any information herein. The information contained in this Current Report on Form 8-K is intended to be considered in the context of more complete information included in the Company’s filings with the SEC and other public announcements that the Company has made and may make from time to time by press release or otherwise. The Company undertakes no…

shall be deemed to be furnished, and not filed: ​ ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press release dated November 10, 2025 entitled “Voyager Reports Third Quarter 2025 Financial and Operating Results”. 104 ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). ​ ​ ​ ​ ​ 2 SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereun…

shall be deemed to be furnished, and not filed: ​ ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press release dated August 6, 2025 entitled “Voyager Reports Second Quarter 2025 Financial and Operating Results”. 104 ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). ​ ​ ​ ​ ​ 2 SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto…

shall be deemed to be furnished, and not filed: ​ ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press release dated May 6, 2025 entitled “Voyager Reports First Quarter 2025 Financial and Operating Results”. 104 ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). ​ ​ ​ ​ ​ 2 SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto dul…

shall be deemed to be furnished, and not filed: ​ ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press release dated March 11, 2025 entitled “Voyager Therapeutics Reports Fourth Quarter and Full Year 2024 Financial and Operating Results”. 104 ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). ​ ​ ​ ​ ​ 2 SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf…

Other Events ALS Program Update On February 11, 2025, Voyager Therapeutics, Inc. (the “Company”) announced that it has decided to assess alternate payloads related to its superoxide dismutase 1 silencing gene therapy program for amyotrophic lateral sclerosis (the “SOD1 ALS Program”). Emerging three-month non-human primate (NHP) data suggest that an alternate payload would be necessary to achieve the Company’s desired product profile for the SOD1 ALS Program. No changes are planned to the nove…

shall be deemed to be furnished, and not filed: ​ ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press release dated November 12, 2024 entitled “Voyager Therapeutics Reports Third Quarter 2024 Financial and Operating Results”. 104 ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). ​ ​ ​ ​ ​ 2 SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the under…

Entry into a Material Definitive Agreement Amendment to Option and License Agreement with Novartis Pharma AG On September 3, 2024 (the “Amendment Effective Date”), Voyager Therapeutics, Inc. (the “Company”) and Novartis Pharma AG (“Novartis”) entered into an amendment (the “Amendment”) to the Option and License Agreement between the Company and Novartis dated March 4, 2022 (the “Agreement”). Pursuant to the Amendment, the Company and Novartis agreed to amend the Agreement to incorporate the g…

shall be deemed to be furnished, and not filed: ​ ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press release dated August 6, 2024 entitled “Voyager Therapeutics Reports Second Quarter 2024 Financial and Operating Results”. 104 ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). ​ ​ ​ ​ ​ 2 SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersi…

Chief Financial Officer — Nathan Jorgensen, Ph.D., M.B.A.: The company hired a new Chief Financial Officer from an external candidate.

shall be deemed to be furnished, and not filed: ​ ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press release dated May 13, 2024 entitled “Voyager Therapeutics Reports First Quarter 2024 Financial and Operating Results”. 104 ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). ​ ​ ​ ​ ​ 2 SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigne…

Chief Financial Officer — Peter P. Pfreundschuh: Mr. Pfreundschuh resigned from his position as Chief Financial Officer and will leave the company after a transition period.

shall be deemed to be furnished, and not filed: ​ ​ ​ ​ Exhibit No. ​ Description ​ ​ ​ 99.1 ​ Press release dated February 28, 2024 entitled “Voyager Therapeutics Reports Fourth Quarter and Full Year 2023 Financial and Operating Results”. 104 ​ Cover Page Interactive Data File (formatted as Inline XBRL and contained in Exhibit 101). ​ ​ ​ ​ ​ 2 SIGNATURES ​ Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its beha…

Entry into a Material Definitive Agreement. On January 4, 2024, Voyager Therapeutics, Inc. (the “Company”) entered into an underwriting agreement (the “Underwriting Agreement”) with Citigroup Global Markets Inc. and Guggenheim Securities, LLC, as representatives of the several underwriters named therein (the “Underwriters”), relating to an underwritten public offering (the “Offering”) of 7,777,778 shares (the “Firm Stock”) of the Company’s common stock, par value $0.001 per share (the “Common…

Other Events. Pricing of Public Offering The full text of the press release issued on January 4, 2024, announcing the pricing of the Offering is attached as Exhibit 99.1 hereto and is incorporated herein by reference. Closing of Novartis Private Placement As previously disclosed, in connection with the execution of a license and collaboration agreement (the “Collaboration Agreement”) between the Company and Novartis Pharma AG (“Novartis”), the Company and Novartis also entered into a stock pu…

Unregistered Sales of Equity Securities The information set forth in

Entry into a Material Definitive Agreement License and Collaboration Agreement On December 28, 2023 (the “Effective Date”), Voyager Therapeutics, Inc. (the “Company”) entered into a License and Collaboration Agreement (the “Collaboration Agreement”) with Novartis Pharma AG (“Novartis”) to (a) provide rights to Novartis with respect to certain proprietary adeno-associated virus (“AAV”) capsids discovered by the Company (the “Voyager Capsids”) for use in the research, development, and commercia…

Other Events Update on VY-TAU01 for the Treatment of Alzheimer’s Disease The Company plans to submit an IND application for VY-TAU01, its anti-tau antibody product candidate for the treatment of Alzheimer’s disease, to the U.S. Food and Drug Administration (the “FDA”) in the first half of 2024. The planned Phase 1 clinical trial is designed to assess the safety of VY-TAU01 in a multi-arm dose escalation study, with a single ascending dose arm expected to be conducted in healthy subjects to be…