Portolan Capital Management Increases Stake in Mayville Engineering Company to 5.92%

On May 28, 2026, Portolan Capital Management, LLC, and its manager George McCabe filed a Schedule 13G disclosing a significant increase in their position in Mayville Engineering Company, Inc. (MEC). As of the event date on May 20, 2026, the reporting persons beneficially own 1,465,004 shares of common stock, representing 5.92% of the company's outstanding shares. This marks a substantial increase from their previous holding of 821,136 shares. Portolan Capital Management, LLC, a registered investment adviser based in Boston, holds sole voting and dispositive power over the entirety of these shares. The filing was made under Rule 13d-1(c), indicating a passive investment intent, as the securities were not acquired to influence or change the control of the issuer. The total value of the reported holdings is approximately $39.75 million. This transaction establishes Portolan Capital Management as a major shareholder in the Milwaukee-based engineering firm.