Form 4: Avidity Biosciences CCO Vests Equity, Sells for Tax

Avidity Biosciences' Chief Commercial Officer, Eric Mosbrooker, acquired 72,000 shares through PSU vesting and subsequently sold shares to cover tax obligations.

Summary

• Eric Mosbrooker, Chief Commercial Officer of Avidity Biosciences, Inc. (RNA), reported transactions on December 17, 2025.
• Acquired 72,000 shares of common stock upon the vesting of performance-based restricted stock units (PSUs) at a price of $0.
• The PSUs were originally granted on October 30, 2024, and were accelerated and settled for tax planning purposes.
• Disposed of 36,564 shares of common stock at $71.87 per share to cover tax withholding related to the PSU settlement.
• Disposed of an additional 11,426 shares of common stock at $71.87 per share to cover tax withholding related to the settlement of other restricted stock units.
• Following these transactions, Eric Mosbrooker beneficially owns 79,010 shares of Avidity Biosciences common stock.

Sentiment

Score: 6

Explanation: The vesting of performance-based restricted stock units (PSUs) suggests that certain performance targets were met, which is a minor positive indicator for the company. However, the transaction is primarily a routine compensation event involving tax-related sales, and it does not provide new material information about the company's strategic direction or financial health, leading to a neutral to slightly positive sentiment.

Positives

• The vesting of performance-based restricted stock units (PSUs) indicates that certain performance targets set by the company were met, reflecting positively on the company's operational achievements.

Risks

• Shares acquired from PSU vesting remain subject to recoupment by Avidity Biosciences if the Chief Commercial Officer's employment is terminated by the Issuer for cause or by the Reporting Person without good reason.

Future Outlook

No specific forward-looking statements or guidance regarding the company's operational or financial performance were provided in this filing.

Industry Context

This filing represents a routine insider transaction common in the biotechnology and pharmaceutical industries, where executive compensation frequently includes equity awards like PSUs and RSUs, which vest over time and often involve tax-related share sales upon settlement.

Stakeholder Impact

• Shareholders: This is a routine insider transaction and does not typically have a significant direct impact on the company's share price or fundamental value. The vesting of PSUs can be seen as a positive signal regarding management's performance against set targets.

Key Dates

Recommendation

This Form 4 details routine equity compensation vesting and tax-related sales by an executive. It does not provide new material information about the company's operational performance, strategic direction, or financial health that would warrant a change in investment recommendation. The vesting of PSUs suggests performance targets were met, which is a minor positive, but the overall impact on the stock's fundamental value is negligible.

Keywords

Avidity Biosciences, RNA, Form 4, Insider Trading, Equity Compensation, PSU, RSU, Stock Vesting, Tax Withholding, Eric Mosbrooker, Chief Commercial Officer