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HowShorted

How shorted is Seres Therapeutics, Inc.? MCRB

#2,460most shorted US stockof 3,805 ranked stocks, more shorted than 35%

3.03%
of shares outstanding reported short · settlement date 15 Sep 2026
vs previous report
−0.56
5 reports (~10 weeks)
+1.39
days to cover
5.72
Aggregate net short position time series for Seres Therapeutics, 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 Seres Therapeutics, 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
5 Aug 20263.28% 31 Jul 20263.70% 14 Aug 2026+0.42
5 May 20265.64% 30 Apr 20265.35% 15 May 2026−0.29
12 Mar 20267.24% 27 Feb 20266.56% 13 Mar 2026−0.68
5 Nov 202510.88% 31 Oct 202510.23% 14 Nov 2025−0.65
13 Mar 202510.09% 28 Feb 20259.59% 14 Mar 2025−0.50
10 Jan 202511.97% 31 Dec 202411.87% 15 Jan 2025−0.10
13 Nov 202411.77% 31 Oct 20249.51% 15 Nov 2024−2.26
13 Aug 202410.84% 31 Jul 202411.04% 15 Aug 2024+0.20

Fails to deliver

The SEC's fails-to-deliver figure for MCRB: 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
546
26 Aug 2026
Highest in window
200,328
21 Nov 2025
Days with a balance
76
Window
16 Sep 2025 to 14 Sep 2026
Aggregate net short position time series for Seres Therapeutics, 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 200K shares.

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Sector: Healthcare

History

Full reported short interest history
Settlement dateShort %Change
15 Sep 20263.03%−0.56
31 Aug 20263.59%−0.11
14 Aug 20263.70%+0.42
31 Jul 20263.28%+0.11
15 Jul 20263.17%+1.53
30 Jun 20261.64%−0.65
15 Jun 20262.29%−2.70
29 May 20264.99%−0.36
15 May 20265.35%−0.29
30 Apr 20265.64%−0.46
15 Apr 20266.10%−0.13
31 Mar 20266.23%−0.33
13 Mar 20266.56%−0.68
27 Feb 20267.24%−1.32
13 Feb 20268.56%−0.58
30 Jan 20269.14%−0.53
15 Jan 20269.67%−0.28
31 Dec 20259.95%−0.99
15 Dec 202510.94%−0.08
28 Nov 202511.02%+0.79
14 Nov 202510.23%−0.65
31 Oct 202510.88%+1.76
15 Oct 20259.12%−0.68
30 Sep 20259.80%−0.89
15 Sep 202510.69%−0.87
29 Aug 202511.56%−0.26
15 Aug 202511.82%+3.07
15 Apr 20258.75%−0.43
31 Mar 20259.18%−0.41
14 Mar 20259.59%−0.50
28 Feb 202510.09%−0.27
14 Feb 202510.36%+0.14
31 Jan 202510.22%−1.65
15 Jan 202511.87%−0.10
31 Dec 202411.97%+0.48
13 Dec 202411.49%+1.31
29 Nov 202410.18%+0.67
15 Nov 20249.51%−2.26
31 Oct 202411.77%−0.13
15 Oct 202411.90%−0.40
30 Sep 202412.30%+0.95
13 Sep 202411.35%+0.84
30 Aug 202410.51%−0.53
15 Aug 202411.04%+0.20
31 Jul 202410.84%−0.42
15 Jul 202411.26%−2.44
28 Jun 202413.70%−1.43
14 Jun 202415.13%+0.17
31 May 202414.96%−0.10
15 May 202415.06%+0.85
30 Apr 202414.21%+2.53
15 Apr 202411.68%−0.77
28 Mar 202412.45%+0.27
15 Mar 202412.18%−0.28
29 Feb 202412.46%+0.40
15 Feb 202412.06%0.00
31 Jan 202412.06%−1.52
12 Jan 202413.58%+0.99
29 Dec 202312.59%−3.51
15 Dec 202316.10%−0.11
30 Nov 202316.21%−1.87
15 Nov 202318.08%+0.20
31 Oct 202317.88%+0.05
13 Oct 202317.83%+1.32
29 Sep 202316.51%+0.60
15 Sep 202315.91%+0.13
31 Aug 202315.78%−2.43
15 Aug 202318.21%+0.33
31 Jul 202317.88%+0.28
14 Jul 202317.60%−0.51
30 Jun 202318.11%+3.63
15 Jun 202314.48%+2.17
31 May 202312.31%+0.40
15 May 202311.91%+2.25
28 Apr 20239.66%+2.56
14 Apr 20237.10%+0.23
31 Mar 20236.87%−0.51
15 Mar 20237.38%+1.11
28 Feb 20236.27%+0.51
15 Feb 20235.76%+0.50
31 Jan 20235.26%−0.01
13 Jan 20235.27%−0.19
30 Dec 20225.46%+1.66
15 Dec 20223.80%+0.38
30 Nov 20223.42%−0.06
15 Nov 20223.48%−0.35
31 Oct 20223.83%−0.15
14 Oct 20223.98%0.00
30 Sep 20223.98%+1.25
15 Sep 20222.73%−0.02
31 Aug 20222.75%+0.13
15 Aug 20222.62%−1.41
29 Jul 20224.03%+0.18
15 Jul 20223.85%−0.22
30 Jun 20224.07%−1.36
15 Jun 20225.43%+0.29
31 May 20225.14%−0.29
13 May 20225.43%+0.02
29 Apr 20225.41%+0.39
14 Apr 20225.02%−0.03
31 Mar 20225.05%−0.87
15 Mar 20225.92%−0.03
28 Feb 20225.95%−0.01
15 Feb 20225.96%−0.06
31 Jan 20226.02%−1.05
14 Jan 20227.07%+0.64
31 Dec 20216.43%−3.36
15 Dec 20219.79%+0.71
30 Nov 20219.08%−0.59
15 Nov 20219.67%+0.16
29 Oct 20219.51%+0.62
15 Oct 20218.89%−1.03
30 Sep 20219.92%+4.09
15 Sep 20215.83%−1.10
31 Aug 20216.93%−0.69
13 Aug 20217.62%+0.44
30 Jul 20217.18%+0.44
15 Jul 20216.74%−0.14
30 Jun 20216.88%−0.56
15 Jun 20217.44%−0.13
28 May 20217.57%−0.19
14 May 20217.76%−0.82
30 Apr 20218.58%−0.13
15 Apr 20218.71%+0.10
31 Mar 20218.61%+0.68
15 Mar 20217.93%+0.74
26 Feb 20217.19%+0.66
12 Feb 20216.53%−1.09
29 Jan 20217.62%−0.42
15 Jan 20218.04%+0.27
31 Dec 20207.77%+2.79
15 Dec 20204.98%−0.36
30 Nov 20205.34%−0.22
13 Nov 20205.56%−0.68
30 Oct 20206.24%−0.54
15 Oct 20206.78%+0.76
30 Sep 20206.02%0.00
15 Sep 20206.02%−0.85
31 Aug 20206.87%−2.35
14 Aug 20209.22%−2.47
31 Jul 202011.69%+1.12
15 Jul 202010.57%+0.32
30 Jun 202010.25%+0.60
15 Jun 20209.65%+0.37
29 May 20209.28%+0.74
15 May 20208.54%+0.56
30 Apr 20207.98%+0.69
15 Apr 20207.29%+0.47
31 Mar 20206.82%−0.59
13 Mar 20207.41%+0.33
28 Feb 20207.08%+0.17
14 Feb 20206.91%+0.13
31 Jan 20206.78%+0.21
15 Jan 20206.57%+0.90
31 Dec 20195.67%+0.35
13 Dec 20195.32%+0.13
29 Nov 20195.19%+0.12
15 Nov 20195.07%+0.22
31 Oct 20194.85%+0.13
15 Oct 20194.72%−0.08
30 Sep 20194.80%+0.47
13 Sep 20194.33%+1.03
30 Aug 20193.30%+0.20
15 Aug 20193.10%−3.92
31 Jul 20197.02%−4.53
15 Jul 201911.55%+1.02
28 Jun 201910.53%−5.78
14 Jun 201916.31%+0.52
31 May 201915.79%+0.69
15 May 201915.10%+2.20
30 Apr 201912.90%−0.40
15 Apr 201913.30%+0.63
29 Mar 201912.67%+0.87
15 Mar 201911.80%+2.08
28 Feb 20199.72%+0.17
15 Feb 20199.55%+0.25
31 Jan 20199.30%−0.36
15 Jan 20199.66%+0.57
31 Dec 20189.09%−0.29
14 Dec 20189.38%−0.01
30 Nov 20189.39%−0.23
15 Nov 20189.62%−0.72
31 Oct 201810.34%−0.70
15 Oct 201811.04%+0.41
28 Sep 201810.63%−0.51
14 Sep 201811.14%−0.15
31 Aug 201811.29%+0.18
15 Aug 201811.11%+0.07
31 Jul 201811.04%+0.06
13 Jul 201810.98%−0.19
29 Jun 201811.17%−0.10
15 Jun 201811.27%−0.42
31 May 201811.69%−0.90
15 May 201812.59%+0.10
30 Apr 201812.49%−0.50
13 Apr 201812.99%−0.66
29 Mar 201813.65%−0.01
15 Mar 201813.66%0.00
28 Feb 201813.66%+0.26
15 Feb 201813.40%−0.06
31 Jan 201813.46%+0.68
12 Jan 201812.78%+0.93
29 Dec 201711.85%–

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

Frequently asked questions

How shorted is Seres Therapeutics, Inc. right now?
3.03% of Seres Therapeutics, Inc.'s (MCRB) shares outstanding were reported short for settlement date 15 Sep 2026, per FINRA's consolidated short interest report. That makes it the 2,460th 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 MCRB'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 MCRB's days to cover?
5.72 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.