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HowShorted

How shorted is Altimmune, Inc.? ALT

#37most shorted US stockof 3,805 ranked stocks, more shorted than 99%

26.60%
of shares outstanding reported short · settlement date 15 Sep 2026
vs previous report
+1.04
5 reports (~10 weeks)
+2.11
days to cover
15.38
Aggregate net short position time series for Altimmune, 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 Altimmune, 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 202626.71% 31 Jul 202626.20% 14 Aug 2026−0.51
13 May 202627.25% 30 Apr 202619.35% 15 May 2026−7.90
5 Mar 202619.60% 27 Feb 202620.36% 13 Mar 2026+0.76
6 Nov 202520.89% 31 Oct 202522.33% 14 Nov 2025+1.44
12 Aug 202531.76% 31 Jul 202528.85% 15 Aug 2025−2.91
13 May 202529.32% 30 Apr 202527.95% 15 May 2025−1.37
27 Feb 202531.60% 14 Feb 202528.13% 28 Feb 2025−3.47
12 Nov 202432.27% 31 Oct 202432.11% 15 Nov 2024−0.16

Fails to deliver

The SEC's fails-to-deliver figure for ALT: 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.

Latest balance
217
14 Sep 2026
Highest in window
262,641
12 Nov 2025
Days with a balance
72
Window
16 Sep 2025 to 14 Sep 2026
Aggregate net short position time series for Altimmune, 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 263K shares.

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

History

Full reported short interest history
Settlement dateShort %Change
15 Sep 202626.60%+1.04
31 Aug 202625.56%−0.64
14 Aug 202626.20%−0.51
31 Jul 202626.71%+1.90
15 Jul 202624.81%+0.32
30 Jun 202624.49%+2.93
15 Jun 202621.56%+1.44
29 May 202620.12%+0.77
15 May 202619.35%−7.90
30 Apr 202627.25%+5.16
15 Apr 202622.09%−0.40
31 Mar 202622.49%+2.13
13 Mar 202620.36%+0.76
27 Feb 202619.60%−4.51
13 Feb 202624.11%+0.93
30 Jan 202623.18%−2.15
15 Jan 202625.33%+0.57
31 Dec 202524.76%+2.01
15 Dec 202522.75%+0.54
28 Nov 202522.21%−0.12
14 Nov 202522.33%+1.44
31 Oct 202520.89%−3.47
15 Oct 202524.36%−5.32
30 Sep 202529.68%+1.26
15 Sep 202528.42%−1.91
29 Aug 202530.33%+1.48
15 Aug 202528.85%−2.91
31 Jul 202531.76%−2.88
15 Jul 202534.64%−3.81
30 Jun 202538.45%+8.37
13 Jun 202530.08%+2.98
30 May 202527.10%−0.85
15 May 202527.95%−1.37
30 Apr 202529.32%+0.18
15 Apr 202529.14%+0.81
31 Mar 202528.33%−0.82
14 Mar 202529.15%+1.02
28 Feb 202528.13%−3.47
14 Feb 202531.60%−1.19
31 Jan 202532.79%−1.79
15 Jan 202534.58%+1.27
31 Dec 202433.31%−0.23
13 Dec 202433.54%+0.59
29 Nov 202432.95%+0.84
15 Nov 202432.11%−0.16
31 Oct 202432.27%+0.99
15 Oct 202431.28%−0.23
30 Sep 202431.51%+0.73
13 Sep 202430.78%−0.18
30 Aug 202430.96%+0.43
15 Aug 202430.53%−0.84
31 Jul 202431.37%−0.51
15 Jul 202431.88%+0.51
28 Jun 202431.37%−1.27
14 Jun 202432.64%−0.47
31 May 202433.11%+0.58
15 May 202432.53%+1.07
30 Apr 202431.46%+2.73
15 Apr 202428.73%+3.72
28 Mar 202425.01%+1.72
15 Mar 202423.29%+3.16
29 Feb 202420.13%−1.37
15 Feb 202421.50%+2.87
31 Jan 202418.63%−1.21
12 Jan 202419.84%+2.27
29 Dec 202317.57%−3.08
15 Dec 202320.65%+8.65
30 Nov 202312.00%−0.52
15 Nov 202312.52%−0.50
31 Oct 202313.02%−1.03
13 Oct 202314.05%+0.48
29 Sep 202313.57%+1.16
15 Sep 202312.41%+0.96
31 Aug 202311.45%+0.47
15 Aug 202310.98%−1.51
31 Jul 202312.49%−2.43
14 Jul 202314.92%+0.80
30 Jun 202314.12%−4.40
15 Jun 202318.52%+0.10
31 May 202318.42%+0.46
15 May 202317.96%−0.38
28 Apr 202318.34%−1.67
14 Apr 202320.01%+0.74
31 Mar 202319.27%+4.25
15 Mar 202315.02%+2.08
28 Feb 202312.94%+0.20
15 Feb 202312.74%+0.18
31 Jan 202312.56%−2.33
13 Jan 202314.89%−0.54
30 Dec 202215.43%+2.53
15 Dec 202212.90%−0.44
30 Nov 202213.34%−1.48
15 Nov 202214.82%+0.06
31 Oct 202214.76%+0.23
14 Oct 202214.53%−1.34
30 Sep 202215.87%+1.94
15 Sep 202213.93%+1.24
31 Aug 202212.69%+2.68
15 Aug 202210.01%−1.24
29 Jul 202211.25%+1.07
15 Jul 202210.18%−3.63
30 Jun 202213.81%−0.44
15 Jun 202214.25%+5.13
31 May 20229.12%+0.20
13 May 20228.92%+1.93
29 Apr 20226.99%+0.43
14 Apr 20226.56%+0.45
31 Mar 20226.11%−3.47
15 Mar 20229.58%−0.34
28 Feb 20229.92%+0.86
15 Feb 20229.06%+0.57
31 Jan 20228.49%−3.04
14 Jan 202211.53%+0.24
31 Dec 202111.29%+0.51
15 Dec 202110.78%−0.07
30 Nov 202110.85%−1.13
15 Nov 202111.98%−2.14
29 Oct 202114.12%−0.28
15 Oct 202114.40%−1.03
30 Sep 202115.43%−1.33
15 Sep 202116.76%+0.70
31 Aug 202116.06%+2.83
13 Aug 202113.23%−0.24
30 Jul 202113.47%−0.70
15 Jul 202114.17%+1.69
30 Jun 202112.48%+1.14
15 Jun 202111.34%−0.04
28 May 202111.38%−2.78
14 May 202114.16%+0.57
30 Apr 202113.59%+0.55
15 Apr 202113.04%−1.54
31 Mar 202114.58%+6.59
15 Mar 20217.99%+1.49
26 Feb 20216.50%−1.13
12 Feb 20217.63%−0.26
29 Jan 20217.89%+0.03
15 Jan 20217.86%−0.99
31 Dec 20208.85%+1.33
15 Dec 20207.52%+0.92
30 Nov 20206.60%−0.70
13 Nov 20207.30%−1.55
30 Oct 20208.85%+1.79
15 Oct 20207.06%+0.73
30 Sep 20206.33%+1.87
15 Sep 20204.46%+1.35
31 Aug 20203.11%+0.40
14 Aug 20202.71%−11.47
15 Jul 202014.18%+1.62
30 Jun 202012.56%−4.63
15 Jun 202017.19%−1.92
29 May 202019.11%+7.02
15 May 202012.09%+1.47
30 Apr 202010.62%−1.06
15 Apr 202011.68%−1.26
31 Mar 202012.94%+11.33
28 Feb 20201.61%+0.04
14 Feb 20201.57%−0.12
31 Jan 20201.69%−0.07
15 Jan 20201.76%−0.30
31 Dec 20192.06%−0.13
13 Dec 20192.19%−0.08
29 Nov 20192.27%−1.71
15 Nov 20193.98%−0.50
31 Oct 20194.48%−0.34
15 Oct 20194.82%–

Newest first. Scroll inside the table for earlier dates, back to 15 Oct 2019.

Frequently asked questions

How shorted is Altimmune, Inc. right now?
26.60% of Altimmune, Inc.'s (ALT) shares outstanding were reported short for settlement date 15 Sep 2026, per FINRA's consolidated short interest report. That makes it the 37th 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 ALT'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 ALT's days to cover?
15.38 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.