Form 4: Amentum CGO Mullen's Scheduled RSU Vesting & Tax Sale

Amentum Holdings' Chief Growth Officer, Sean Thomas Mullen, filed a Form 4 disclosing a pre-scheduled vesting of 9,298 restricted stock units and the subsequent sale of 4,194 shares for tax withholding, both set for December 17, 2025.

Summary

• Sean Thomas Mullen, Chief Growth Officer of Amentum Holdings, Inc. (AMTM), filed a Form 4 on December 19, 2025.
• The filing reports a pre-scheduled transaction under a Rule 10b5-1 plan, with the transaction date set for December 17, 2025.
• On December 17, 2025, 9,298 restricted stock units (RSUs) are scheduled to vest, resulting in the acquisition of 9,298 shares of AMTM common stock.
• Concurrently, 4,194 shares of AMTM common stock are scheduled to be disposed of at a price of $28.67 per share to cover tax withholding obligations related to the RSU vesting.
• Following these transactions, Mr. Mullen's beneficial ownership of AMTM common stock is expected to be 26,138 shares.
• Each restricted stock unit represents a contingent right to receive one share of AMTM common stock.

Sentiment

Score: 6

Explanation: The filing reports a routine, pre-scheduled executive compensation event (RSU vesting and tax-related share sale). This is a neutral event, reflecting compensation realization rather than a discretionary investment decision or significant operational news.

Positives

• The vesting of 9,298 restricted stock units represents a realization of executive compensation for the Chief Growth Officer.
• The transaction is pre-scheduled under a Rule 10b5-1 plan, indicating a structured and pre-planned approach to insider stock transactions.

Negatives

• The disposition of 4,194 shares, even for tax withholding purposes, reduces the Chief Growth Officer's direct beneficial ownership in the company.

Future Outlook

The filing details a pre-scheduled executive compensation event set for December 17, 2025, under a Rule 10b5-1 plan. It does not provide broader forward-looking statements or guidance regarding the company's operational or financial performance.

Industry Context

This Form 4 filing is a routine disclosure of an insider stock transaction, specifically the vesting of restricted stock units and a tax-related sale. Such events are common across publicly traded companies as part of executive compensation packages and do not inherently reflect specific industry trends or competitive positioning for Amentum Holdings, Inc.

Stakeholder Impact

• Shareholders: The transaction is a routine executive compensation event and is unlikely to have a significant direct impact on shareholders. It provides transparency into insider holdings.
• Employees: The vesting of RSUs is a standard component of executive compensation, aligning executive interests with long-term company performance.

Key Dates

Keywords

Amentum Holdings, AMTM, Form 4, Insider Transaction, Restricted Stock Units, RSU Vesting, Executive Compensation, Rule 10b5-1 Plan, Stock Sale, Tax Withholding