Atara Biotherapeutics, Inc.

SecurityATRA / Atara Biotherapeutics, Inc.
InstitutionUBS Group AG
Latest Disclosed Ownership50,070 shares
Latest Disclosed Value $ 236,831
UBS Group AG reports 3,484.11% increase in ownership of ATRA / Atara Biotherapeutics, Inc.

On May 5, 2026 - UBS Group AG filed a 13F-HR form disclosing ownership of 50,070 shares of Atara Biotherapeutics, Inc. (US:ATRA) valued at $236,831 USD as of March 31, 2026. The entity filed a previous 13F-HR on January 29, 2026 disclosing 1,397 shares of Atara Biotherapeutics, Inc.. This represents a change in shares of 3,484.11% during the quarter. The current value of the position is $514,219 USD.

Institutional Ownership: 13F and NPORT Filings

The Security and Class in the table below are shown exactly as filed by the investor. We do our best to track continuity of investments through acquisitions, and this will be reflected in the table as changes in names. In addition to descriptive data, performance of the investment is shown over time. To calculate quarterly performance, we first calculate cost basis of the shares purchased during the quarter, then use that to calculate gross profit. Quarterly return is Gross Profit / Starting Portfolio value.

Note that cost basis is calculated and stored in thousands, so small quarterly changes in shares frequently result in a cost basis of zero.

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Disclosed Equity Positions (from 13F/NPORT Filings)
File
Date		 Effective
Date		Form Security Class ID Avg Price
Paid (Est)		 Reported
Shares		 ΔShares ΔShares
(%)		 Reported
Value
(x1000)		 ΔValue
(%)		 Alloc
(%)		 ΔAlloc ΔAlloc (%) Cost Basis
(x1000)		 Unrealized
Gain/Loss
(x1000)
2026-05-05 2026-03-31 13F ATARA BIOTHERAPEUTICS COM NEW 046513206 50,070 48,673 3,484.11 237 844.00 0.0000
2026-01-29 2025-12-31 13F ATARA BIOTHERAPEUTICS COM NEW 046513206 1,397 -15,871 -91.91 25 -89.88 0.0000
2025-11-13 2025-09-30 13F ATARA BIOTHERAPEUTICS COM NEW 046513206 17,268 8,883 105.94 247 285.94 0.0000
2025-08-14 2025-06-30 13F ATARA BIOTHERAPEUTICS COM NEW 046513206 8,385 -15,949 -65.54 65 -55.56 0.0000
2025-05-13 2025-03-31 13F ATARA BIOTHERAPEUTICS COM NEW 046513206 24,334 23,500 2,817.75 145 1,209.09 0.0000
2025-02-14 2024-12-31 13F ATARA BIOTHERAPEUTICS COM NEW 046513206 834 432 107.46 11 266.67 0.0000
2024-11-14 2024-09-30 13F ATARA BIOTHERAPEUTICS COM NEW 046513206 402 -1 -0.25 3 0.00 0.0000
2024-08-14 2024-06-30 13F ATARA BIOTHERAPEUTICS COM NEW 046513206 403 403 3 0.0000
Legend
Shares
The total number of shares held by the institution at the end of the reporting period (the effective date). This is provided in the filing.
Value
The total value of the shares as of the effective date. This is provided in the filing.
Avg. Share Price
The weighted average share price of the shares held by the institution. We use FIFO accounting to determine this price
Class
This is the security class as indicated by the filer. There are a variety of values for this field. Common values include "EC" = equity common, "EP" - equity preferred
Allocation (%)
The percent of the institution's portfolio that this position represents. This is provided in NPORT filings. For 13F filings, we calculate it.
Change in Allocation
The change in allocation from the prior reporting period. This is calculated as current allocation - prior allocation.
Change in Allocation (%)
The percent change in allocation from the prior reporting period. This is calculated as (current allocation - prior allocation) / prior allocation.
Cost Basis
The total cost of the shares held. This is calculated as reported shares * avg. share price
Unrealized Gain/Loss
This is the market value of the position as of the effective date minus the cost basis.