Greenstreet Yvonne 4

What Happened Yvonne Greenstreet, CEO of Alnylam Pharmaceuticals, sold a total of 2,933 shares in multiple open-market transactions on March 4, 2026, generating approximately $947,581 in gross proceeds. The individual lots reported were:

• 135 shares @ $319.03 = $43,069
• 129 shares @ $320.01 = $41,281
• 274 shares @ $320.81 = $87,902
• 368 shares @ $321.82 = $118,430
• 444 shares @ $323.01 = $143,416
• 973 shares @ $323.84 = $315,096
• 345 shares @ $324.88 = $112,084
• 265 shares @ $325.67 = $86,303

These transactions are reported as sales (S). According to the filing footnote, many of the shares were automatically sold by the company to satisfy mandatory tax withholding obligations upon the vesting of restricted stock units (sell-to-cover), which is a routine administrative event rather than an open-ended directional bet.

Key Details

• Transaction date: March 4, 2026. Prices ranged roughly from $318.27 to $326.21 (weighted-average ranges explained in footnotes).
• Total shares sold: 2,933; total proceeds: about $947,581.
• Shares owned after transaction: not disclosed in the provided filing extract.
• Notable footnotes: F1 = mandatory sell-to-cover for tax withholding; F2–F9 = weighted-average price ranges for multiple trades; F10 (listed in the filing) refers to 401(k) matching contributions but is not directly tied to these sales.
• Filing timeliness: filed March 6, 2026 (appears timely based on the March 4 transaction date).

Context

• Sell-to-cover transactions occur when shares vest (e.g., RSUs) and a portion is sold automatically to cover required tax withholding; these are administrative and do not necessarily indicate the insider is reducing overall exposure by choice.
• Transaction code: S = Sale. No 10b5-1 plan, gift, or option exercise was indicated for these sales in the provided information.
• For retail investors: purchases by insiders can be more informative about bullish conviction, while routine sell-to-cover sales are common and typically tax-driven.