Form 4 Filing for Atara Biotherapeutics, Inc.

This filing reports a transaction by Nguyen AnhCo, President and CEO of Atara Biotherapeutics, Inc. On May 18, 2026, 5,241 shares of Common Stock were disposed of with a transaction code "S". This disposal was to satisfy tax withholding obligations related to the vesting of previously granted restricted stock units, executed through a sale-to-cover provision. The average price per share was $9.1289, with sales occurring in multiple transactions at prices ranging from $9.12 to $9.40. Following this transaction, Nguyen AnhCo holds 137,837 shares of Common Stock. The filing is labeled as an OFFICER_DIRECTOR_CHANGE due to the nature of the transaction related to executive compensation and stock vesting.