ATRA S-3: Shelf registration

Atara Biotherapeutics

Filed with the SEC on Nov 10, 2026 · accession 0001104659-26-125314

ATRA filed a S-3 (shelf registration) with the SEC on Nov 10, 2026. Atara Biotherapeutics filed a replacement Form S-3 shelf registration statement covering up to $200 million in securities, including an at-the-market (ATM) equity offering program of up to $23,011,805 in common stock through TD Cowen. The stock moved -1.0% by the first close after the filing.

Summary of the filing

Atara Biotherapeutics filed a replacement Form S-3 shelf registration statement covering up to $200 million in securities, including an at-the-market (ATM) equity offering program of up to $23,011,805 in common stock through TD Cowen. The filing replaces a prior registration statement expiring November 13, 2026.

For details, click here →How to read a S-3 →

Key details

Maximum aggregate offering amount under base prospectus$200.0M

Maximum aggregate offering amount under ATM sales agreement prospectus$23.0M

RegistrantAtara Biotherapeutics, Inc.

Sales agent for atm programTD Securities (USA) LLC (TD Cowen)

Original sales agent, succeeded by td cowenCowen and Company, LLC

Legal counselSidley Austin LLP

President and chief executive officerAnhCo Thieu Nguyen

Interim chief financial officerKevin G. Sarney

How ATRA stock reacted

Close before

$8.18

Nov 9, 2026

First close after

-0.98%

$8.10

5 trading days

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Since filing

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Frequently asked questions

What did ATRA file with the SEC on Nov 10, 2026?

ATRA filed a S-3 (Shelf registration). Atara Biotherapeutics filed a replacement Form S-3 shelf registration statement covering up to $200 million in securities, including an at-the-market (ATM) equity offering program of up to $23,011,805 in common stock through TD Cowen. The filing replaces a prior registration statement expiring November 13, 2026.

What does a shelf registration mean for ATRA stock?

New shares dilute existing holders and are often sold at a discount to the market price.

How do I read a S-3?

Lets the company sell shares or debt later, quickly — a sign more shares may come. Check the maximum amount and compare it with the company’s size. A later "424B" filing shows an actual sale under the shelf.

Why are SEC filings important?

Public companies must tell the SEC about anything that can change their value — results, leadership changes, big deals, new shares, bankruptcy. Filings are the official source, often before the news. A S-3 (shelf registration): Lets the company sell shares or debt later, quickly — a sign more shares may come.

How did ATRA stock react to this filing?

ATRA closed at $8.18 before the filing and $8.10 on Nov 10, 2026 (-0.98%).

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