Skip to content
HowShorted

How shorted is Atara Biotherapeutics, Inc.? ATRA

#2,038most shorted US stockof 3,805 ranked stocks, more shorted than 46%

4.03%
of shares outstanding reported short · settlement date 15 Sep 2026
vs previous report
−0.23
5 reports (~10 weeks)
−0.39
days to cover
7.34
Aggregate net short position time series for Atara Biotherapeutics, Inc.

Markers along the chart's base: ▲ results announced (an 8-K reporting results was filed) ▲ quarterly or annual report filed. Dates are SEC filing dates; hover a point to see events since the previous settlement.

Days to cover

FINRA's own figure: reported shares short divided by the stock's average daily trading volume, published alongside each settlement. It expresses the short position in days of typical trading rather than as a percentage of the company; the two can move differently.

Aggregate net short position time series for Atara Biotherapeutics, Inc. days to cover

Short interest around results

For each results announcement (an 8-K reporting results, by its SEC filing date), the FINRA settlement before it and the first one after. Settlements fall twice a month, so the two figures can sit up to a month apart and much else changes in between: this shows what was reported, not why.

Reported short interest before and after each results announcement
Results filedSettlement beforeSettlement afterChange
12 Aug 20266.57% 31 Jul 20264.75% 14 Aug 2026−1.82
16 Mar 20263.83% 13 Mar 20264.00% 31 Mar 2026+0.17
12 Jan 20262.35% 31 Dec 20253.92% 30 Jan 2026+1.57
12 Nov 20252.40% 31 Oct 20252.45% 14 Nov 2025+0.05
11 Aug 20253.60% 31 Jul 20252.79% 15 Aug 2025−0.81
14 Jul 20254.55% 30 Jun 20254.57% 15 Jul 2025+0.02
15 May 20258.91% 30 Apr 20256.27% 30 May 2025−2.64
7 Mar 202512.21% 28 Feb 202512.34% 14 Mar 2025+0.13

Fails to deliver

The SEC's fails-to-deliver figure for ATRA: the aggregate net balance of shares that failed to be delivered at each settlement date, published by the SEC twice a month and shown here verbatim for the trailing window. A balance is not a daily flow, and a fail has many ordinary causes; the SEC says it cannot guarantee the accuracy of the data. See what fails to deliver are and the largest balances today.

Last balance on file
805
8 Sep 2026
Highest in window
79,847
14 Jan 2026
Days with a balance
100
Window
16 Sep 2025 to 14 Sep 2026
Aggregate net short position time series for Atara Biotherapeutics, Inc. fails to deliver

Source: U.S. Securities and Exchange Commission, fails-to-deliver data (public domain). Only settlement days with a positive balance appear; the largest balance in the window was 80K shares.

Embed this chart

Paste this snippet to embed the interactive chart. It updates with each FINRA report and keeps the source attribution. Preview

Download chart cardShare on XRedditLinkedIn
Cite this page
Plain
Wikipedia
BibTeX

Sector: Healthcare · By year: 2018 · 2019 · 2020 · 2021 · 2022 · 2023 · 2024 · 2025 · 2026

History

Full reported short interest history
Settlement dateShort %Change
15 Sep 20264.03%−0.23
31 Aug 20264.26%−0.49
14 Aug 20264.75%−1.82
31 Jul 20266.57%−0.49
15 Jul 20267.06%+2.64
30 Jun 20264.42%−1.60
15 Jun 20266.02%+0.10
29 May 20265.92%−0.76
15 May 20266.68%+2.94
30 Apr 20263.74%−0.15
15 Apr 20263.89%−0.11
31 Mar 20264.00%+0.17
13 Mar 20263.83%−0.75
27 Feb 20264.58%+1.68
13 Feb 20262.90%−1.02
30 Jan 20263.92%+1.57
31 Dec 20252.35%+0.04
15 Dec 20252.31%+0.03
28 Nov 20252.28%−0.17
14 Nov 20252.45%+0.05
31 Oct 20252.40%+0.57
15 Oct 20251.83%−0.30
30 Sep 20252.13%−0.17
15 Sep 20252.30%−0.18
29 Aug 20252.48%−0.31
15 Aug 20252.79%−0.81
31 Jul 20253.60%−0.97
15 Jul 20254.57%+0.02
30 Jun 20254.55%−0.33
13 Jun 20254.88%−1.39
30 May 20256.27%−0.78
15 May 20257.05%−1.86
30 Apr 20258.91%−2.39
15 Apr 202511.30%−0.08
31 Mar 202511.38%−0.96
14 Mar 202512.34%+0.13
28 Feb 202512.21%+0.50
14 Feb 202511.71%−0.56
31 Jan 202512.27%+2.76
15 Jan 20259.51%+0.25
31 Dec 20249.26%−0.31
13 Dec 20249.57%+0.13
29 Nov 20249.44%+0.42
15 Nov 20249.02%−3.93
31 Oct 202412.95%−0.05
15 Oct 202413.00%+2.29
30 Sep 202410.71%+1.29
13 Sep 20249.42%+1.07
30 Aug 20248.35%+0.65
15 Aug 20247.70%−1.33
14 Jun 20249.03%−0.41
31 May 20249.44%−0.29
15 May 20249.73%−0.22
30 Apr 20249.95%+0.36
15 Apr 20249.59%+0.18
28 Mar 20249.41%−1.41
15 Mar 202410.82%+0.87
29 Feb 20249.95%−0.72
15 Feb 202410.67%+3.28
31 Jan 20247.39%+0.20
12 Jan 20247.19%−1.82
29 Dec 20239.01%−0.93
15 Dec 20239.94%−0.96
30 Nov 202310.90%+2.89
15 Nov 20238.01%−4.24
31 Oct 202312.25%+0.11
13 Oct 202312.14%+0.73
29 Sep 202311.41%−0.13
15 Sep 202311.54%+0.14
31 Aug 202311.40%−0.66
15 Aug 202312.06%−1.16
31 Jul 202313.22%+0.34
14 Jul 202312.88%+0.94
30 Jun 202311.94%−1.54
15 Jun 202313.48%+0.60
31 May 202312.88%−1.59
15 May 202314.47%−4.08
28 Apr 202318.55%−1.48
14 Apr 202320.03%−0.78
31 Mar 202320.81%+3.40
15 Mar 202317.41%+2.74
28 Feb 202314.67%+0.07
15 Feb 202314.60%−0.19
31 Jan 202314.79%+0.43
13 Jan 202314.36%+0.65
30 Dec 202213.71%+0.65
15 Dec 202213.06%+0.15
30 Nov 202212.91%+0.21
15 Nov 202212.70%+0.07
31 Oct 202212.63%+0.02
14 Oct 202212.61%−0.44
30 Sep 202213.05%−0.03
15 Sep 202213.08%+1.20
31 Aug 202211.88%−0.07
15 Aug 202211.95%+0.78
29 Jul 202211.17%+2.56
15 Jul 20228.61%−2.85
30 Jun 202211.46%−0.61
15 Jun 202212.07%−0.49
31 May 202212.56%+0.76
13 May 202211.80%−0.83
29 Apr 202212.63%+0.06
14 Apr 202212.57%+1.57
31 Mar 202211.00%+1.12
15 Mar 20229.88%+1.68
28 Feb 20228.20%+0.21
15 Feb 20227.99%+0.11
31 Jan 20227.88%+1.16
14 Jan 20226.72%−3.94
31 Dec 202110.66%+0.36
15 Dec 202110.30%+0.47
30 Nov 20219.83%−0.33
15 Nov 202110.16%−2.09
29 Oct 202112.25%−0.69
15 Oct 202112.94%−0.89
30 Sep 202113.83%−0.89
15 Sep 202114.72%+0.30
31 Aug 202114.42%−0.66
13 Aug 202115.08%−0.33
30 Jul 202115.41%+1.04
15 Jul 202114.37%+0.50
30 Jun 202113.87%−1.16
15 Jun 202115.03%−0.07
28 May 202115.10%−0.10
14 May 202115.20%+0.76
30 Apr 202114.44%−1.64
15 Apr 202116.08%−0.80
31 Mar 202116.88%+1.81
15 Mar 202115.07%+0.78
26 Feb 202114.29%−0.81
12 Feb 202115.10%−0.11
29 Jan 202115.21%+0.72
15 Jan 202114.49%−0.94
31 Dec 202015.43%−0.60
15 Dec 202016.03%+0.15
30 Nov 202015.88%−1.79
13 Nov 202017.67%−2.04
30 Oct 202019.71%−1.07
15 Oct 202020.78%+1.71
30 Sep 202019.07%+0.61
15 Sep 202018.46%−2.08
31 Aug 202020.54%+0.88
14 Aug 202019.66%+0.67
31 Jul 202018.99%−6.01
15 Jul 202025.00%+2.00
30 Jun 202023.00%+3.12
15 Jun 202019.88%−0.25
29 May 202020.13%−1.17
15 May 202021.30%+0.98
30 Apr 202020.32%+1.42
15 Apr 202018.90%+0.71
31 Mar 202018.19%+0.19
13 Mar 202018.00%−0.14
28 Feb 202018.14%+0.93
14 Feb 202017.21%−0.40
31 Jan 202017.61%−0.98
15 Jan 202018.59%+0.56
31 Dec 201918.03%+0.36
13 Dec 201917.67%−1.60
29 Nov 201919.27%+0.94
15 Nov 201918.33%−1.78
31 Oct 201920.11%+0.04
15 Oct 201920.07%+1.31
30 Sep 201918.76%+2.95
13 Sep 201915.81%−0.76
30 Aug 201916.57%+0.63
15 Aug 201915.94%+0.84
31 Jul 201915.10%−5.18
15 Jul 201920.28%+3.13
28 Jun 201917.15%−0.83
14 Jun 201917.98%+0.75
31 May 201917.23%+0.33
15 May 201916.90%+1.93
30 Apr 201914.97%−0.21
15 Apr 201915.18%−0.49
29 Mar 201915.67%−1.57
15 Mar 201917.24%+0.39
28 Feb 201916.85%+0.92
15 Feb 201915.93%+1.84
31 Jan 201914.09%+0.05
15 Jan 201914.04%−0.33
31 Dec 201814.37%−0.46
14 Dec 201814.83%+0.49
30 Nov 201814.34%+0.24
15 Nov 201814.10%−0.28
31 Oct 201814.38%+1.22
15 Oct 201813.16%−0.99
28 Sep 201814.15%+0.44
14 Sep 201813.71%+0.07
31 Aug 201813.64%−0.46
15 Aug 201814.10%−0.88
31 Jul 201814.98%−0.27
13 Jul 201815.25%−0.97
29 Jun 201816.22%+0.97
15 Jun 201815.25%−0.72
31 May 201815.97%+0.97
15 May 201815.00%−0.40
30 Apr 201815.40%−6.40
13 Apr 201821.80%+4.07
29 Mar 201817.73%+3.58
15 Mar 201814.15%−2.15
28 Feb 201816.30%−0.10
15 Feb 201816.40%+0.66
31 Jan 201815.74%−1.23
12 Jan 201816.97%+1.23
29 Dec 201715.74%–

Newest first. Scroll inside the table for earlier dates, back to 29 Dec 2017.

Frequently asked questions

How shorted is Atara Biotherapeutics, Inc. right now?
4.03% of Atara Biotherapeutics, Inc.'s (ATRA) shares outstanding were reported short for settlement date 15 Sep 2026, per FINRA's consolidated short interest report. That makes it the 2,038th most shorted US stock, out of 3,805 we rank.
What does this number include?
FINRA member firms must report their short positions in all US equities twice a month; FINRA consolidates them per security. We divide that official share count by the company's shares outstanding from its SEC filings. This is the regulatory figure, not a daily estimate.
Why does it only update twice a month?
US short interest is reported for settlement on the 15th and the last business day of each month, and FINRA publishes the consolidated figures about nine business days later. That cadence is set by regulation; no daily official figure exists.
Is this ATRA's short float?
No. This is short interest as a percentage of shares outstanding, the count in the company's SEC filings. "Short float" divides the same FINRA short count by the public float, which excludes closely held shares, so it comes out higher for the same company. We publish no float estimates: the float is not a regulatory figure.
What is ATRA's days to cover?
7.34 days for settlement date 15 Sep 2026: FINRA's own short interest ratio, the reported shares short divided by average daily trading volume. It is published in the same FINRA file and shown verbatim; we hold no volume data ourselves.
Which funds are short?
US public short interest is aggregate-only: individual short sellers are not named. Only some EU markets publish named positions.