A group of ARCH Venture-affiliated entities and individuals filed a Schedule 13D with the SEC on November 9, 2026, disclosing a combined beneficial ownership position in Aspen Neuroscience, Inc. common stock as of a triggering event dated November 2, 2026.

Key Highlights

  • Aggregate beneficial ownership: Each reporting person disclosed beneficial ownership of 3,754,922 shares of Aspen Neuroscience, Inc. common stock, par value $0.0001 per share.
  • Percentage of class: The 3,754,922 shares represent 12.9% of the class, according to the filing.
  • Triggering event date: The date of the event requiring this filing was November 2, 2026, as stated on the cover page.
  • Shared voting and dispositive power: All reporting persons listed 0 sole voting power and 0 sole dispositive power, with 3,754,922 shares held under shared voting and shared dispositive power.
  • Source of funds: The limited partnership entities listed working capital (WC) as their source of funds; the general partner entities and individuals listed affiliated funds (AF).
  • Reporting entities: The filing covers eight entities - including ARCH Venture Fund X, L.P., ARCH Venture Fund XIV, L.P., and related general partner entities - as well as individuals Robert Nelsen, Keith Crandell, and Kristina Burow.
  • CUSIP: The CUSIP number for the covered securities is 044933109.

ARCH Venture Group Discloses 3,754,922-Share Position in Aspen Neuroscience

According to the Schedule 13D filed November 9, 2026, a group of entities and individuals affiliated with ARCH Venture Management, LLC reported a combined beneficial ownership of 3,754,922 shares of common stock of Aspen Neuroscience, Inc. The filing lists the contact person as Mark McDonnell of ARCH Venture Management, LLC, located at 8755 W. Higgins Road Suite 1025, Chicago, IL 60631. The triggering event that required submission of a Schedule 13D - rather than the lighter-disclosure Schedule 13G - is dated November 2, 2026.

The filing covers eight distinct legal entities and three named individuals. The entities include ARCH Venture Fund X, L.P.; ARCH Venture Partners X, L.P.; ARCH Venture Fund X Overage, L.P.; ARCH Venture Partners X Overage, L.P.; ARCH Venture Partners X, LLC; ARCH Venture Fund XIV, L.P.; ARCH Venture Partners XIV, L.P.; and ARCH Venture Partners XIV, LLC. Each of these entities, together with individuals Robert Nelsen, Keith Crandell, and Kristina Burow (whose cover-page entry appears partially truncated in the filing), reports the identical aggregate figure of 3,754,922 shares, representing 12.9% of the class. All reporting persons list sole voting power and sole dispositive power at zero, with all 3,754,922 shares attributed to shared voting and shared dispositive power.

The limited partnership entities indicated working capital as the source of funds, while the general partner entities and the named individuals indicated affiliated funds. All entities are organized in Delaware. The common stock covered is identified by CUSIP 044933109. The filing notes that if the reporting persons previously filed a Schedule 13G and are now filing a Schedule 13D, the applicable regulatory provisions would include Sections 240.13d-1(e), 240.13d-1(f), or 240.13d-1(g).

What Was Disclosed

ARCH Venture-affiliated entities and individuals filed a Schedule 13D disclosing shared beneficial ownership of 3,754,922 shares, or 12.9%, of Aspen Neuroscience, Inc. common stock, with a triggering event date of November 2, 2026.