Brown Advisory Inc. and four affiliated entities filed Amendment No. 6 to a Schedule 13G with the SEC on November 13, 2026, disclosing beneficial ownership of 2,025,770 shares of SI-BONE, Inc. common stock as of September 30, 2026.

Key Highlights

  • Aggregate beneficial ownership: Brown Advisory Inc. reported 2,025,770 shares, representing 4.52% of SI-BONE, Inc. common stock.
  • Voting power: Brown Advisory Inc. holds sole voting power over 1,813,676 shares and shared voting power over 0 shares.
  • Dispositive power: Brown Advisory Inc. holds shared dispositive power over all 2,025,770 shares, with sole dispositive power of 0.
  • Subsidiaries included: The filing covers four subsidiaries - Brown Investment Advisory & Trust Co., Brown Advisory LLC, Signature Financial Management, Inc., and Brown Advisory Ltd.
  • Largest subsidiary position: Brown Advisory LLC reported 2,015,623 shares beneficially owned, equaling 4.5% of the class.
  • Triggering event date: The date of the event requiring this filing was September 30, 2026.

Brown Advisory's SI-BONE Ownership Structure Across Five Entities

According to the filing, Brown Advisory Inc., a Maryland-incorporated parent holding company, submitted Amendment No. 6 to Schedule 13G on behalf of itself and four subsidiaries. The aggregate beneficial ownership reported for Brown Advisory Inc. stands at 2,025,770 shares of SI-BONE, Inc. common stock, representing 4.52% of the class. The filing states that all sole dispositive power is 0 for every reporting person, with shared dispositive power accounting for the full reported positions at each entity level.

At the subsidiary level, Brown Advisory LLC - classified as an investment adviser - holds the largest individual position, reporting 2,015,623 shares with shared dispositive power and sole voting power over 1,803,851 shares. Brown Investment Advisory & Trust Co., classified as a bank and incorporated in Maryland, reported 6,242 shares with shared dispositive power and sole voting power over the same 6,242 shares. Signature Financial Management, Inc., a Virginia-incorporated investment adviser, reported 1,216 shares with shared dispositive power and sole voting power over 894 shares. Brown Advisory Ltd, incorporated in the United Kingdom, reported 2,689 shares with shared dispositive power and sole voting power over the full 2,689 shares.

The filing states that "the total securities being reported are beneficially owned by investment companies and other managed accounts of direct/indirect subsidiaries of Brown Advisory Inc." and that "applicable investment advisory contracts provide voting and/or investment power over securities." The filing further certifies that the securities "were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer."

What Was Disclosed

Brown Advisory Inc. and four subsidiaries disclosed a combined beneficial ownership of 2,025,770 shares of SI-BONE, Inc. common stock, equal to 4.52% of the class, as of September 30, 2026, via a Schedule 13G amendment filed November 13, 2026.