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HowShorted

How shorted is Ultragenyx Pharmaceutical Inc.? RARE

#221most shorted US stockof 3,805 ranked stocks, more shorted than 94%

16.81%
of shares outstanding reported short · settlement date 15 Sep 2026
vs previous report
−0.58
5 reports (~10 weeks)
+0.34
days to cover
2.22
Aggregate net short position time series for Ultragenyx Pharmaceutical 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 Ultragenyx Pharmaceutical 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
4 Aug 202615.18% 31 Jul 202616.12% 14 Aug 2026+0.94
5 May 202614.14% 30 Apr 202614.19% 15 May 2026+0.05
12 Feb 20269.43% 30 Jan 202610.21% 13 Feb 2026+0.78
12 Jan 20268.31% 31 Dec 20259.19% 15 Jan 2026+0.88
4 Nov 20257.41% 31 Oct 20258.11% 14 Nov 2025+0.70
5 Aug 20257.93% 31 Jul 20258.72% 15 Aug 2025+0.79
6 May 20255.98% 30 Apr 20256.23% 15 May 2025+0.25
13 Feb 20254.51% 31 Jan 20254.63% 14 Feb 2025+0.12

Fails to deliver

The SEC's fails-to-deliver figure for RARE: 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
108
11 Sep 2026
Highest in window
233,066
3 Jun 2026
Days with a balance
36
Window
16 Sep 2025 to 14 Sep 2026
Aggregate net short position time series for Ultragenyx Pharmaceutical 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 233K shares.

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Sector: Healthcare

History

Full reported short interest history
Settlement dateShort %Change
15 Sep 202616.81%−0.58
31 Aug 202617.39%+1.27
14 Aug 202616.12%+0.94
31 Jul 202615.18%+1.54
15 Jul 202613.64%−2.83
30 Jun 202616.47%+1.94
15 Jun 202614.53%−0.40
29 May 202614.93%+0.74
15 May 202614.19%+0.05
30 Apr 202614.14%+1.63
15 Apr 202612.51%+0.70
31 Mar 202611.81%+1.53
13 Mar 202610.28%+0.35
27 Feb 20269.93%−0.28
13 Feb 202610.21%+0.78
30 Jan 20269.43%+0.24
15 Jan 20269.19%+0.88
31 Dec 20258.31%−0.60
15 Dec 20258.91%−0.29
28 Nov 20259.20%+1.09
14 Nov 20258.11%+0.70
31 Oct 20257.41%−1.61
15 Oct 20259.02%+1.08
30 Sep 20257.94%−0.31
15 Sep 20258.25%−0.38
29 Aug 20258.63%−0.09
15 Aug 20258.72%+0.79
31 Jul 20257.93%−1.38
15 Jul 20259.31%+2.10
30 Jun 20257.21%+0.78
13 Jun 20256.43%+0.56
30 May 20255.87%−0.36
15 May 20256.23%+0.25
30 Apr 20255.98%+0.08
15 Apr 20255.90%+1.01
31 Mar 20254.89%−0.31
14 Mar 20255.20%+0.24
28 Feb 20254.96%+0.33
14 Feb 20254.63%+0.12
31 Jan 20254.51%−0.09
15 Jan 20254.60%+0.25
31 Dec 20244.35%+0.33
13 Dec 20244.02%+0.36
29 Nov 20243.66%+0.04
15 Nov 20243.62%+0.18
31 Oct 20243.44%+0.01
15 Oct 20243.43%+0.30
30 Sep 20243.13%−0.79
13 Sep 20243.92%+0.11
30 Aug 20243.81%−0.36
15 Aug 20244.17%−0.42
31 Jul 20244.59%−0.66
15 Jul 20245.25%+0.15
28 Jun 20245.10%−0.96
14 Jun 20246.06%+0.69
31 May 20245.37%+0.15
15 May 20245.22%−0.37
30 Apr 20245.59%+0.25
15 Apr 20245.34%+0.57
28 Mar 20244.77%+0.17
15 Mar 20244.60%−0.11
29 Feb 20244.71%+0.38
15 Feb 20244.33%+0.17
31 Jan 20244.16%−0.85
12 Jan 20245.01%+0.07
29 Dec 20234.94%+0.87
15 Dec 20234.07%+0.13
30 Nov 20233.94%−0.32
15 Nov 20234.26%−0.81
31 Oct 20235.07%+0.40
13 Oct 20234.67%−0.83
29 Sep 20235.50%+0.75
15 Sep 20234.75%−0.07
31 Aug 20234.82%−0.09
15 Aug 20234.91%−0.06
31 Jul 20234.97%−0.63
14 Jul 20235.60%+0.34
30 Jun 20235.26%+0.95
15 Jun 20234.31%−0.18
31 May 20234.49%−0.44
15 May 20234.93%+0.69
28 Apr 20234.24%+0.17
14 Apr 20234.07%−0.36
31 Mar 20234.43%+0.19
15 Mar 20234.24%−0.15
28 Feb 20234.39%−0.29
15 Feb 20234.68%−0.18
31 Jan 20234.86%−0.23
13 Jan 20235.09%+0.29
30 Dec 20224.80%−0.05
15 Dec 20224.85%+0.60
30 Nov 20224.25%−0.06
15 Nov 20224.31%+0.09
31 Oct 20224.22%−0.41
14 Oct 20224.63%+0.26
30 Sep 20224.37%−0.09
15 Sep 20224.46%+0.27
31 Aug 20224.19%−0.16
15 Aug 20224.35%+0.30
29 Jul 20224.05%−0.22
15 Jul 20224.27%+0.13
30 Jun 20224.14%+0.28
15 Jun 20223.86%+0.02
31 May 20223.84%−0.48
13 May 20224.32%−0.09
29 Apr 20224.41%+0.25
14 Apr 20224.16%+0.10
31 Mar 20224.06%−0.17
15 Mar 20224.23%−0.13
28 Feb 20224.36%−0.41
15 Feb 20224.77%−0.33
31 Jan 20225.10%−0.02
14 Jan 20225.12%+0.03
31 Dec 20215.09%−0.66
15 Dec 20215.75%−0.08
30 Nov 20215.83%−0.15
15 Nov 20215.98%+0.55
29 Oct 20215.43%−0.25
15 Oct 20215.68%−0.23
30 Sep 20215.91%+0.22
15 Sep 20215.69%−0.24
31 Aug 20215.93%−0.04
13 Aug 20215.97%−0.03
30 Jul 20216.00%+0.15
15 Jul 20215.85%+0.25
30 Jun 20215.60%−1.73
15 Jun 20217.33%−0.20
28 May 20217.53%−0.07
14 May 20217.60%−0.49
30 Apr 20218.09%+0.02
15 Apr 20218.07%−0.16
31 Mar 20218.23%−0.04
15 Mar 20218.27%−0.49
26 Feb 20218.76%+0.83
12 Feb 20217.93%−0.80
29 Jan 20218.73%−0.29
15 Jan 20219.02%−0.52
31 Dec 20209.54%−0.78
15 Dec 202010.32%−0.45
30 Nov 202010.77%−0.43
13 Nov 202011.20%−0.39
30 Oct 202011.59%−0.61
15 Oct 202012.20%+0.63
30 Sep 202011.57%+0.21
15 Sep 202011.36%+0.17
31 Aug 202011.19%−0.10
14 Aug 202011.29%−1.95
31 Jul 202013.24%−0.18
15 Jul 202013.42%+0.58
30 Jun 202012.84%+0.43
15 Jun 202012.41%−0.30
29 May 202012.71%+0.11
15 May 202012.60%−0.24
30 Apr 202012.84%+0.01
15 Apr 202012.83%−0.14
31 Mar 202012.97%+0.97
13 Mar 202012.00%+0.77
28 Feb 202011.23%+0.16
14 Feb 202011.07%−0.51
31 Jan 202011.58%+0.45
15 Jan 202011.13%−0.12
31 Dec 201911.25%+0.65
13 Dec 201910.60%−1.30
29 Nov 201911.90%−0.75
15 Nov 201912.65%+1.60
31 Oct 201911.05%+0.49
15 Oct 201910.56%–

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

Frequently asked questions

How shorted is Ultragenyx Pharmaceutical Inc. right now?
16.81% of Ultragenyx Pharmaceutical Inc.'s (RARE) shares outstanding were reported short for settlement date 15 Sep 2026, per FINRA's consolidated short interest report. That makes it the 221st 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 RARE'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 RARE's days to cover?
2.22 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.