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ATRA — structural market context

Atara Biotherapeutics, Inc. Co

Structural market context from public regulatory and market data, shown with its as-of dates. Descriptive only: nothing on this page is a recommendation, a prediction, or advice to buy or sell any security.

What changed

As of the close on Oct 21. Each line shows the earlier value, the later value and their dates.

Price

Close $9.35 (Oct 21) vs $9.16 (Oct 20): +2.07%.

Volume

0.76× its 20-session average (35K) on Oct 21.

Includes pre- and post-market trading.

Short interest

Short interest 322K shares (settlement Sep 30) vs 404K (Sep 15).

No new publication in this window. Latest: settlement Sep 30, published Oct 10.

Fails-to-deliver

Latest file (settlements Sep 15–Sep 30, published Oct 16): 4 days with fails, largest 4K shares on Sep 28.

Previous file (settlements Sep 1–Sep 14, published Sep 30): 2 days with fails, largest 1K shares on Sep 1.

No new publication in this window.

Insider filings (Form 4)

None recorded in this window.

ATRA short interest & days to cover

SHARES SHORT
322K
% OF FLOAT
4.6%
DAYS TO COVER
8.1
CHANGE VS PRIOR
-20.4%

FINRA consolidated short interest, reported twice a month and published ~2 weeks after each settlement date. % of float uses reported free float. · as of 2026-09-30 (22d ago)

ATRA fails-to-deliver (FTD)

Settlement dateFailed sharesPrice
2026-09-29 · 23d194$8.37
2026-09-28 · 24d4K$8.81
2026-09-24 · 28d828$8.56

SEC fails-to-deliver files, published twice a month with ~6 weeks of delay.

ATRA insider buying and selling (Form 4)

Last 12 months, Form 4 codes P and S: 1 purchase · 1 sale

InsiderTypeSharesValueFiled
Cherry Brian N · directorPurchase (P)104K$1000K2026-09-04
Nguyen AnhCo · director, officer: President and CEOSale (S)5K$41K2026-08-26

SEC Form 4 filings: purchases and sales reported on Form 4 (transaction codes P and S) only; grants and option exercises excluded. Attributed public records.

Frequently asked questions

What is ATRA's short interest?
As of the FINRA settlement date 2026-09-30, ATRA had 322K shares sold short — 4.6% of its float, with 8.1 days to cover at average volume. FINRA publishes this data roughly two weeks after each twice-monthly settlement, so it is inherently delayed. A short-interest figure describes an aggregate position; it does not predict what the stock will do.
Are insiders buying ATRA?
In the last 12 months of SEC Form 4 filings, ATRA recorded 1 insider purchase and 1 sale reported on Form 4 (transaction codes P and S; grants and option exercises excluded). These are attributed public records — information, not instruction.
Is this page telling me to buy or sell ATRA?
No. Everything on this page is descriptive, structural market context from public data, shown with its as-of dates. TradeAI News does not issue directional recommendations, price predictions, or buy/sell advice — for any ticker.
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ATRA: the full history

Latest rows shown. Full history, market-wide screens, cluster detection and the context journal live in the dashboard.

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Not financial advice. Trading involves risk. Descriptive structural context, never a recommendation.