Atara Biotherapeutics, Inc. (ATRA) Institutional Ownership

Ownership Summary

Atara Biotherapeutics, Inc. (NASDAQ:ATRA) currently has 5 active institutional owners and shareholders as of today (December 2025), that have filed 13F forms with the Securities Exchange Commission (SEC).

• These investors collectively held 2.2% of the company's total shares outstanding in December 2025, down from 14.0% in September 2025.
• In percentage terms, this reflects as a holdings change of 4.28% quarter on quarter, and a decrease of 88.64% year over year.
• Among the 5 institutional holders of Atara Biotherapeutics, 2 added to their stakes while 1 trimmed their positions and 2 held steady.
• The aggregate institutional position in Atara Biotherapeutics now stands at 301.61K shares as of December 2025, after investors increased their holdings (up by 12.39K shares quarter on quarter which is down 2.07Mn shares year over year).
• VANGUARD GROUP INC continues to be the largest institutional holder of Atara Biotherapeutics as of December 31, 2025, with a position of 225.94K shares, representing 1.68% of the company's outstanding stock.
• Among the most significant buyers of Atara Biotherapeutics during December 2025 were VANGUARD GROUP INC (22.50K), Cambridge Investment Research Advisors, Inc. (5.75K).
• Leading sellers of Atara Biotherapeutics stock in December 2025 included UBS Group AG (15.87K).
• The top 5 institutional holders of Atara Biotherapeutics for the quarter ending December 2025 included VANGUARD GROUP INC (225.94K), STALEY CAPITAL ADVISERS INC (50.00K), Cambridge Investment Research Advisors, Inc. (22.86K), SBI Securities Co., Ltd. (1.40K), UBS Group AG (1.40K).