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How shorted was Mersana Therapeutics, Inc.? MRSN

Mersana Therapeutics, Inc. left the US market in 2025. This page is a frozen archive of its reported short interest, ending 14 Nov 2025. The ticker MRSN no longer refers to this company and may since have been reassigned.
6.01%
of shares outstanding reported short · settlement date 14 Nov 2025
vs previous report
−0.47
5 reports (~10 weeks)
−2.67
days to cover
1.00
Aggregate net short position time series for Mersana 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 Mersana 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
13 Aug 20256.36% 15 Jul 20257.72% 15 Aug 2025+1.36
15 May 20258.45% 30 Apr 20258.91% 30 May 2025+0.46
3 Mar 20258.28% 28 Feb 20256.97% 14 Mar 2025−1.31
13 Nov 20248.05% 31 Oct 20247.62% 15 Nov 2024−0.43
13 Aug 20247.45% 31 Jul 20246.92% 15 Aug 2024−0.53
9 May 20249.05% 30 Apr 20247.35% 15 May 2024−1.70
28 Feb 20245.89% 15 Feb 20245.92% 29 Feb 2024+0.03
7 Nov 20239.36% 31 Oct 202311.44% 15 Nov 2023+2.08
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Sector: Healthcare

History

Full reported short interest history
Settlement dateShort %Change
14 Nov 20256.01%−0.47
31 Oct 20256.48%+0.39
15 Oct 20256.09%−1.98
30 Sep 20258.07%−0.48
15 Sep 20258.55%−0.13
29 Aug 20258.68%+0.96
15 Aug 20257.72%+1.36
15 Jul 20256.36%−2.85
30 Jun 20259.21%−2.88
13 Jun 202512.09%+3.18
30 May 20258.91%−1.35
15 May 202510.26%+1.81
30 Apr 20258.45%+0.38
15 Apr 20258.07%+0.30
31 Mar 20257.77%+0.80
14 Mar 20256.97%−1.31
28 Feb 20258.28%+0.87
14 Feb 20257.41%−0.25
31 Jan 20257.66%−0.39
15 Jan 20258.05%+0.89
31 Dec 20247.16%−0.05
13 Dec 20247.21%+0.12
29 Nov 20247.09%−0.53
15 Nov 20247.62%−0.43
31 Oct 20248.05%−0.08
15 Oct 20248.13%+0.36
30 Sep 20247.77%−0.63
13 Sep 20248.40%+0.02
30 Aug 20248.38%+1.46
15 Aug 20246.92%−0.53
31 Jul 20247.45%−0.37
15 Jul 20247.82%−0.09
28 Jun 20247.91%−0.63
14 Jun 20248.54%−0.50
31 May 20249.04%+1.69
15 May 20247.35%−1.70
30 Apr 20249.05%+0.28
15 Apr 20248.77%+0.37
28 Mar 20248.40%+1.16
15 Mar 20247.24%+1.32
29 Feb 20245.92%+0.03
15 Feb 20245.89%+0.37
31 Jan 20245.52%−0.61
12 Jan 20246.13%−0.83
29 Dec 20236.96%−0.05
15 Dec 20237.01%−2.83
30 Nov 20239.84%−1.60
15 Nov 202311.44%+2.08
31 Oct 20239.36%+0.01
13 Oct 20239.35%+0.89
29 Sep 20238.46%−1.02
15 Sep 20239.48%+0.73
31 Aug 20238.75%−1.31
15 Aug 202310.06%−1.65
31 Jul 202311.71%+6.36
14 Jul 20235.35%−0.16
30 Jun 20235.51%+1.13
15 Jun 20234.38%−0.76
31 May 20235.14%−0.53
15 May 20235.67%−1.69
28 Apr 20237.36%+0.08
14 Apr 20237.28%−0.04
31 Mar 20237.32%+1.04
15 Mar 20236.28%−0.72
28 Feb 20237.00%+1.17
15 Feb 20235.83%+0.11
31 Jan 20235.72%+0.49
13 Jan 20235.23%+0.17
30 Dec 20225.06%+0.54
15 Dec 20224.52%−0.24
30 Nov 20224.76%+0.02
15 Nov 20224.74%−0.81
31 Oct 20225.55%−0.38
14 Oct 20225.93%+0.43
30 Sep 20225.50%+1.52
15 Sep 20223.98%+0.30
31 Aug 20223.68%+0.12
15 Aug 20223.56%−1.05
29 Jul 20224.61%−1.12
15 Jul 20225.73%−1.38
30 Jun 20227.11%−0.09
15 Jun 20227.20%+0.16
31 May 20227.04%+1.47
13 May 20225.57%+0.44
29 Apr 20225.13%+0.98
14 Apr 20224.15%−0.14
31 Mar 20224.29%−1.37
15 Mar 20225.66%+0.50
28 Feb 20225.16%−0.69
15 Feb 20225.85%−1.97
31 Jan 20227.82%+0.98
14 Jan 20226.84%+0.81
31 Dec 20216.03%+0.09
15 Dec 20215.94%0.00
30 Nov 20215.94%−0.09
15 Nov 20216.03%−0.92
29 Oct 20216.95%−0.30
15 Oct 20217.25%−0.06
30 Sep 20217.31%+0.09
15 Sep 20217.22%−0.53
31 Aug 20217.75%−1.13
13 Aug 20218.88%−0.96
30 Jul 20219.84%−0.15
15 Jul 20219.99%−0.68
30 Jun 202110.67%−1.74
15 Jun 202112.41%+0.26
28 May 202112.15%−0.33
14 May 202112.48%+0.41
30 Apr 202112.07%−0.49
15 Apr 202112.56%−1.76
31 Mar 202114.32%+1.73
15 Mar 202112.59%−0.25
26 Feb 202112.84%+0.45
12 Feb 202112.39%+0.40
29 Jan 202111.99%+0.29
15 Jan 202111.70%+0.76
31 Dec 202010.94%+1.12
15 Dec 20209.82%−0.51
30 Nov 202010.33%+0.17
13 Nov 202010.16%+0.61
30 Oct 20209.55%−0.45
15 Oct 202010.00%+0.22
30 Sep 20209.78%+1.56
15 Sep 20208.22%−0.31
31 Aug 20208.53%−0.01
14 Aug 20208.54%+0.34
31 Jul 20208.20%+0.47
15 Jul 20207.73%+0.08
30 Jun 20207.65%+2.47
15 Jun 20205.18%−1.12
29 May 20206.30%+2.10
15 May 20204.20%−0.77
30 Apr 20204.97%+0.12
15 Apr 20204.85%−0.02
31 Mar 20204.87%−0.22
13 Mar 20205.09%−0.27
28 Feb 20205.36%+0.43
14 Feb 20204.93%+0.16
31 Jan 20204.77%+1.02
15 Jan 20203.75%+1.51
31 Dec 20192.24%+0.51
13 Dec 20191.73%+0.22
29 Nov 20191.51%−0.06
15 Nov 20191.57%+0.05
31 Oct 20191.52%+0.26
15 Oct 20191.26%–

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

Frequently asked questions

How shorted was Mersana Therapeutics, Inc.?
Mersana Therapeutics, Inc. left the US market in 2025. Its final reported figure was 6.01% of shares outstanding for settlement date 14 Nov 2025, per FINRA's consolidated short interest report; this page preserves its full history.
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 MRSN'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 MRSN's days to cover?
1.00 days for settlement date 14 Nov 2025: 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.