Atara Biotherapeutics, Inc.

ATRA

Form 4 • Statement of Changes in Beneficial Ownership

SEC Accession Number: 0000905148-26-001144
Filing date: Mar 4, 2026
Earliest execution date: Mar 2, 2026

Summary

Type

Sell

Net shares

-2,104

% of shares

-6.21%

Amount (USD)

$10,690

Insider confidence score

46.3 out of 100

Positive

  • Tax withholding obligation
  • Small sell amount (<$50K)

Negative

  • Large tax withholding sell (≥1% of shares)

Stock transactions

Transaction 1

Security

Common Stock

Action

Sell

Date

2026-03-02

Code

S

Net shares

-24.0

Price per Share

$5.08

Amount (USD)

$121.85

Acquired/Disposed

Disposed

Shares Owned Before

33,854.0

Shares Owned After

33,830.0

Transaction 2

Security

Common Stock

Action

Sell

Date

2026-03-02

Code

S

Net shares

-1,603.0

Price per Share

$5.08

Amount (USD)

$8,144.84

Acquired/Disposed

Disposed

Shares Owned Before

33,830.0

Shares Owned After

32,227.0

Transaction 3

Security

Common Stock

Action

Sell

Date

2026-03-02

Code

S

Net shares

-377.0

Price per Share

$5.08

Amount (USD)

$1,915.91

Acquired/Disposed

Disposed

Shares Owned Before

32,227.0

Shares Owned After

31,850.0

Transaction 4

Security

Common Stock

Action

Sell

Date

2026-03-02

Code

S

Net shares

-100.0

Price per Share

$5.08

Amount (USD)

$508.30

Acquired/Disposed

Disposed

Shares Owned Before

31,850.0

Shares Owned After

31,750.0

Filing's footnotes

1. Shares sold automatically to satisfy tax withholding obligations in connection with the vesting of previously granted restricted stock units, pursuant to a sale-to-cover provision in the award agreement.

2. The sale price of the reporting person's shares represents the weighted average price of all shares sold by a broker on March 2, 2026 on behalf of a group of employees of the Issuer to satisfy the payment of withholding tax liability of such employees.

3. This amount includes 400 shares purchased under the Issuer's Employee Stock Purchase Plan on November 28, 2025.

This page is for informational purposes only. While we strive for accuracy, the summary may contain inaccuracies or omissions. Please refer to the official SEC filing for authoritative information. Open the SEC filing.