SCHEDULE 13G/A: William Blair Investment Management Discloses 4.2% Passive Stake in ADTRAN Holdings

William Blair Investment Management, LLC has filed an amended Schedule 13G, reporting a 4.2% beneficial ownership stake in ADTRAN Holdings, Inc. as of March 31, 2025.

Summary

• William Blair Investment Management, LLC, an investment adviser, has filed an Amendment No. 2 to Schedule 13G regarding its beneficial ownership in ADTRAN Holdings, Inc.
• As of March 31, 2025, William Blair Investment Management, LLC beneficially owns an aggregate of 3,354,334 shares of ADTRAN Holdings, Inc. Common Stock.
• This ownership represents 4.2% of the class of securities.
• The firm holds sole voting power over 2,184,298 shares and sole dispositive power over 3,354,334 shares.
• The filing certifies that the securities were acquired and are held in the ordinary course of business and not for the purpose of changing or influencing the control of ADTRAN Holdings, Inc.

Sentiment

Score: 5

Explanation: The document is a standard beneficial ownership disclosure (Schedule 13G/A) indicating a passive investment. It contains no positive or negative performance data or strategic announcements from the issuer, thus maintaining a neutral sentiment.

Positives

• The filing indicates a continued investment by a reputable investment management firm, William Blair Investment Management, LLC, in ADTRAN Holdings, Inc.
• The investment is stated to be for ordinary course of business, suggesting a passive, long-term investment approach rather than an activist one.

Negatives

• The document does not contain any negative information regarding ADTRAN Holdings, Inc. or the investment.

Risks

• The document does not explicitly mention any risks related to ADTRAN Holdings, Inc. or the investment.

Future Outlook

This Schedule 13G filing does not provide any forward-looking statements or guidance regarding ADTRAN Holdings, Inc.'s future performance or William Blair Investment Management, LLC's future investment intentions beyond the passive nature of the current holding.

Management Comments

• "By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under 240.14a-11." (Certification by Stephanie Braming, Partner, Global Head of Investment Management, William Blair Investment Management, LLC)

Industry Context

This filing is a routine disclosure of an institutional investor's passive stake in a publicly traded company. It reflects an investment firm's portfolio allocation rather than a specific industry trend or competitive action. ADTRAN Holdings, Inc. operates in the telecommunications networking and broadband access solutions industry.

Stakeholder Impact

• Shareholders: Provides transparency regarding a significant institutional investor's passive stake in the company, which can offer some level of confidence or insight into institutional interest.

Key Dates

Keywords

ADTRAN Holdings, William Blair Investment Management, Schedule 13G, Beneficial Ownership, Common Stock, Investment Adviser, SEC Filing, Passive Investment