Form 4: Avidity Biosciences CCO Sells Shares Under 10b5-1 Plan

Avidity Biosciences' Chief Commercial Officer, Eric Mosbrooker, exercised stock options and subsequently sold 6,562 shares of common stock for a weighted-average price of $45.3781 per share under a pre-arranged Rule 10b5-1 trading plan.

Summary

• Eric Mosbrooker, Chief Commercial Officer of Avidity Biosciences, Inc. (RNA), reported transactions on October 3, 2025.
• Mosbrooker exercised options to acquire 6,562 shares of common stock at an exercise price of $9.05 per share.
• Concurrently, he sold 6,562 shares of common stock at a weighted-average price of $45.3781 per share, with individual sales ranging from $44.80 to $47.21.
• These transactions were conducted pursuant to a Rule 10b5-1 trading plan adopted on September 11, 2024.
• Following these transactions, Mosbrooker directly beneficially owns 55,000 shares of common stock and 177,188 stock options.
• The remaining stock options vest at a rate of 1/48th monthly from January 1, 2024, fully vesting on the fourth anniversary of that date.

Sentiment

Score: 5

Explanation: The filing reports a routine insider transaction (exercise and sale) under a pre-arranged 10b5-1 plan. This type of transaction is generally neutral, reflecting personal financial management rather than a direct positive or negative signal about the company's immediate prospects.

Positives

• The officer's exercise of options indicates a profitable personal financial event, as the exercise price ($9.05) was significantly lower than the sale price ($45.3781).
• The transactions were executed under a pre-arranged Rule 10b5-1 trading plan, which suggests a planned financial management strategy rather than a reaction to new, undisclosed information.

Negatives

• The sale of shares by a Chief Commercial Officer, even under a 10b5-1 plan, could be perceived by some investors as a reduction in insider holdings, although it is often a routine liquidity event.

Risks

• No specific company-related operational or financial risks are disclosed in this Form 4 filing.

Future Outlook

This Form 4 filing does not contain any forward-looking statements or guidance regarding the company's future performance or strategic outlook.

Industry Context

This filing reports a routine insider transaction under a pre-arranged trading plan, which is common across all industries for executives managing their personal finances and equity compensation. It does not provide specific insights into broader biotechnology industry trends or competitive positioning.

Stakeholder Impact

• Shareholders: May observe the Chief Commercial Officer's sale of shares, which could be interpreted neutrally as personal financial planning or slightly negatively as a reduction in insider holdings, though mitigated by the 10b5-1 plan.

Key Dates

Keywords

Avidity Biosciences, RNA, Form 4, Insider Trading, Stock Option Exercise, Share Sale, Eric Mosbrooker, Chief Commercial Officer, 10b5-1 Plan, Biotechnology