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HowShorted

How shorted is Amphastar Pharmaceuticals, Inc.? AMPH

#506most shorted US stockof 3,805 ranked stocks, more shorted than 86%

11.74%
of shares outstanding reported short · settlement date 15 Sep 2026
vs previous report
−0.33
5 reports (~10 weeks)
+3.02
days to cover
10.75
Aggregate net short position time series for Amphastar Pharmaceuticals, 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 Amphastar Pharmaceuticals, 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
6 Aug 202611.59% 31 Jul 202612.66% 14 Aug 2026+1.07
7 May 20267.80% 30 Apr 20268.57% 15 May 2026+0.77
26 Feb 20268.09% 13 Feb 20267.96% 27 Feb 2026−0.13
6 Nov 20259.13% 31 Oct 20257.81% 14 Nov 2025−1.32
7 Aug 20258.54% 31 Jul 20258.89% 15 Aug 2025+0.35
7 May 20256.67% 30 Apr 20258.50% 15 May 2025+1.83
27 Feb 20258.47% 14 Feb 20258.59% 28 Feb 2025+0.12
6 Nov 20248.92% 31 Oct 20248.81% 15 Nov 2024−0.11

Fails to deliver

The SEC's fails-to-deliver figure for AMPH: 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
787
14 Sep 2026
Highest in window
13,708
20 Aug 2026
Days with a balance
51
Window
16 Sep 2025 to 14 Sep 2026
Aggregate net short position time series for Amphastar Pharmaceuticals, 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 14K shares.

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Sector: Healthcare

History

Full reported short interest history
Settlement dateShort %Change
15 Sep 202611.74%−0.33
31 Aug 202612.07%−0.59
14 Aug 202612.66%+1.07
31 Jul 202611.59%+2.12
15 Jul 20269.47%+0.75
30 Jun 20268.72%+0.10
15 Jun 20268.62%+0.12
29 May 20268.50%−0.07
15 May 20268.57%+0.77
30 Apr 20267.80%−0.69
15 Apr 20268.49%+0.81
31 Mar 20267.68%−0.46
13 Mar 20268.14%+0.18
27 Feb 20267.96%−0.13
13 Feb 20268.09%−0.27
30 Jan 20268.36%+0.08
15 Jan 20268.28%−0.63
31 Dec 20258.91%+0.24
15 Dec 20258.67%+1.39
28 Nov 20257.28%−0.53
14 Nov 20257.81%−1.32
31 Oct 20259.13%−0.10
15 Oct 20259.23%+0.68
30 Sep 20258.55%−0.33
15 Sep 20258.88%−0.06
29 Aug 20258.94%+0.05
15 Aug 20258.89%+0.35
31 Jul 20258.54%+0.04
15 Jul 20258.50%−0.12
30 Jun 20258.62%−0.04
13 Jun 20258.66%−0.03
30 May 20258.69%+0.19
15 May 20258.50%+1.83
30 Apr 20256.67%+0.50
15 Apr 20256.17%−0.95
31 Mar 20257.12%−0.89
14 Mar 20258.01%−0.58
28 Feb 20258.59%+0.12
14 Feb 20258.47%−0.10
31 Jan 20258.57%−1.00
15 Jan 20259.57%−0.44
31 Dec 202410.01%+0.93
13 Dec 20249.08%+0.50
29 Nov 20248.58%−0.23
15 Nov 20248.81%−0.11
31 Oct 20248.92%+0.22
15 Oct 20248.70%−0.24
30 Sep 20248.94%+0.46
13 Sep 20248.48%−0.17
30 Aug 20248.65%0.00
15 Aug 20248.65%−0.65
31 Jul 20249.30%+0.64
15 Jul 20248.66%+0.14
28 Jun 20248.52%+0.04
14 Jun 20248.48%+0.78
31 May 20247.70%−0.01
15 May 20247.71%−0.61
30 Apr 20248.32%+0.25
15 Apr 20248.07%+0.40
28 Mar 20247.67%+0.16
15 Mar 20247.51%−0.26
29 Feb 20247.77%+0.27
15 Feb 20247.50%+0.83
31 Jan 20246.67%+0.52
12 Jan 20246.15%+0.34
29 Dec 20235.81%−0.09
15 Dec 20235.90%−0.05
30 Nov 20235.95%−0.08
15 Nov 20236.03%+0.91
31 Oct 20235.12%−0.32
13 Oct 20235.44%+0.08
29 Sep 20235.36%−0.15
15 Sep 20235.51%+2.85
31 Aug 20232.66%−0.39
15 Aug 20233.05%+0.09
31 Jul 20232.96%−1.33
14 Jul 20234.29%+0.12
30 Jun 20234.17%−0.14
15 Jun 20234.31%+0.42
31 May 20233.89%−0.04
15 May 20233.93%+0.07
28 Apr 20233.86%+0.88
14 Apr 20232.98%+0.26
31 Mar 20232.72%−0.30
15 Mar 20233.02%−0.61
28 Feb 20233.63%+0.04
15 Feb 20233.59%+0.04
31 Jan 20233.55%+0.03
13 Jan 20233.52%−0.04
30 Dec 20223.56%−0.08
15 Dec 20223.64%−0.03
30 Nov 20223.67%−0.14
15 Nov 20223.81%−0.14
31 Oct 20223.95%+0.05
14 Oct 20223.90%+0.05
30 Sep 20223.85%−0.39
15 Sep 20224.24%−0.23
31 Aug 20224.47%+0.06
15 Aug 20224.41%−0.34
29 Jul 20224.75%−0.15
15 Jul 20224.90%+0.12
30 Jun 20224.78%−0.62
15 Jun 20225.40%+0.53
31 May 20224.87%−0.35
13 May 20225.22%+0.34
29 Apr 20224.88%+0.65
14 Apr 20224.23%+0.18
31 Mar 20224.05%−0.14
15 Mar 20224.19%+0.04
28 Feb 20224.15%−0.13
15 Feb 20224.28%+0.23
31 Jan 20224.05%−0.07
14 Jan 20224.12%−0.07
31 Dec 20214.19%−0.15
15 Dec 20214.34%−0.08
30 Nov 20214.42%+0.28
15 Nov 20214.14%−0.67
29 Oct 20214.81%+0.05
15 Oct 20214.76%+0.01
30 Sep 20214.75%−0.28
15 Sep 20215.03%+0.03
31 Aug 20215.00%+0.16
13 Aug 20214.84%−0.19
30 Jul 20215.03%−0.08
15 Jul 20215.11%−0.03
30 Jun 20215.14%−0.46
15 Jun 20215.60%+0.11
28 May 20215.49%+0.02
14 May 20215.47%−0.07
30 Apr 20215.54%+0.18
15 Apr 20215.36%+0.15
31 Mar 20215.21%+0.15
15 Mar 20215.06%−0.34
26 Feb 20215.40%+0.03
12 Feb 20215.37%−0.10
29 Jan 20215.47%+0.08
15 Jan 20215.39%−0.24
31 Dec 20205.63%+0.20
15 Dec 20205.43%−0.19
30 Nov 20205.62%−0.05
13 Nov 20205.67%+0.01
30 Oct 20205.66%−0.14
15 Oct 20205.80%+0.16
30 Sep 20205.64%+0.38
15 Sep 20205.26%−0.06
31 Aug 20205.32%+0.03
14 Aug 20205.29%−0.51
31 Jul 20205.80%+0.11
15 Jul 20205.69%−0.41
30 Jun 20206.10%−0.54
15 Jun 20206.64%−0.28
29 May 20206.92%+0.01
15 May 20206.91%−0.10
30 Apr 20207.01%+0.54
15 Apr 20206.47%+0.22
31 Mar 20206.25%−0.12
13 Mar 20206.37%+0.36
28 Feb 20206.01%+0.28
14 Feb 20205.73%−0.06
31 Jan 20205.79%−0.01
15 Jan 20205.80%+0.04
31 Dec 20195.76%−0.33
13 Dec 20196.09%+1.06
29 Nov 20195.03%+0.46
15 Nov 20194.57%+0.36
31 Oct 20194.21%+0.17
15 Oct 20194.04%+0.01
30 Sep 20194.03%−0.18
13 Sep 20194.21%+0.59
30 Aug 20193.62%+0.53
15 Aug 20193.09%+0.09
31 Jul 20193.00%+0.12
15 Jul 20192.88%+0.04
28 Jun 20192.84%+0.19
14 Jun 20192.65%−0.23
31 May 20192.88%−0.04
15 May 20192.92%0.00
30 Apr 20192.92%−0.24
15 Apr 20193.16%−0.06
29 Mar 20193.22%−0.04
15 Mar 20193.26%+0.07
28 Feb 20193.19%−0.18
15 Feb 20193.37%−0.15
31 Jan 20193.52%−0.12
15 Jan 20193.64%+0.16
31 Dec 20183.48%−0.04
14 Dec 20183.52%+0.30
30 Nov 20183.22%−0.04
15 Nov 20183.26%−0.22
31 Oct 20183.48%−0.06
15 Oct 20183.54%−0.09
28 Sep 20183.63%+0.06
14 Sep 20183.57%+0.16
31 Aug 20183.41%+0.17
15 Aug 20183.24%+0.08
31 Jul 20183.16%+0.13
13 Jul 20183.03%−0.16
29 Jun 20183.19%0.00
15 Jun 20183.19%−0.45
31 May 20183.64%+0.34
15 May 20183.30%+0.07
30 Apr 20183.23%+0.11
13 Apr 20183.12%−0.02
29 Mar 20183.14%−0.13
15 Mar 20183.27%−0.34
28 Feb 20183.61%+0.01
15 Feb 20183.60%−1.19
31 Jan 20184.79%−0.03
12 Jan 20184.82%−0.20
29 Dec 20175.02%–

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

Frequently asked questions

How shorted is Amphastar Pharmaceuticals, Inc. right now?
11.74% of Amphastar Pharmaceuticals, Inc.'s (AMPH) shares outstanding were reported short for settlement date 15 Sep 2026, per FINRA's consolidated short interest report. That makes it the 506th 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 AMPH'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 AMPH's days to cover?
10.75 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.