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Cytosorbents Corp

CTSO
Exchange
Nasdaq
Industry
Surgical & Medical Instruments & Apparatus
SEC CIK
0001175151

In the last 90 days, Cytosorbents Corp insiders filed 4 open-market purchases and 0 sales; 50 institutions reported holding it in 13F filings for Q2 2026, worth $6.04M in total; no superinvestor holds it.

Four kinds of short-selling data, each measuring something different:

  • Short interest: shares sold short and not yet bought back, as of a settlement date. FINRA publishes it twice a month, about eight business days after the settlement date.
  • Daily short volume: shares sold short each day in off-exchange trades reported to FINRA. It counts trades, not open positions, and is published the next day.
  • Fails-to-deliver: shares not delivered by the settlement date. The SEC publishes them twice a month, about two weeks late.
  • ATS (dark pool) volume: weekly volume on alternative trading systems and other off-exchange venues. FINRA publishes it two to four weeks after the week.

More in the glossary.

Short interest

Shares sold short and not yet bought back, from FINRA, on every settlement date in the last two years.

Short interest
134.9K
Shares, settlement Oct 30, 2026
Change
+20.5K
+17.9% vs. Oct 15, 2026
Days to cover
1.11
Short interest ÷ average daily volume
Average daily volume
121.5K
Shares, as reported by FINRA
Short interest by settlement date
Oct 31, 2024: 1,355,760 sharesNov 15, 2024: 1,298,947 sharesNov 29, 2024: 1,369,474 sharesDec 13, 2024: 1,397,411 sharesDec 31, 2024: 1,447,610 sharesJan 15, 2025: 1,833,139 sharesJan 31, 2025: 1,934,385 sharesFeb 14, 2025: 1,950,582 sharesFeb 28, 2025: 1,850,036 sharesMar 14, 2025: 1,842,019 sharesMar 31, 2025: 1,745,606 sharesApr 15, 2025: 1,624,985 sharesApr 30, 2025: 1,505,054 sharesMay 15, 2025: 1,485,065 sharesMay 30, 2025: 1,463,783 sharesJun 13, 2025: 1,433,439 sharesJun 30, 2025: 1,481,862 sharesJul 15, 2025: 1,438,944 sharesJul 31, 2025: 1,367,365 sharesAug 15, 2025: 1,489,774 sharesAug 29, 2025: 1,387,175 sharesSep 15, 2025: 1,348,578 sharesSep 30, 2025: 1,342,026 sharesOct 15, 2025: 1,317,259 sharesOct 31, 2025: 1,566,174 sharesNov 14, 2025: 1,952,028 sharesNov 28, 2025: 2,013,299 sharesDec 15, 2025: 1,995,957 sharesDec 31, 2025: 2,002,634 sharesJan 15, 2026: 1,985,895 sharesJan 30, 2026: 2,036,463 sharesFeb 13, 2026: 2,039,234 sharesFeb 27, 2026: 2,000,812 sharesMar 13, 2026: 2,018,660 sharesMar 31, 2026: 2,020,680 sharesApr 15, 2026: 2,044,318 sharesApr 30, 2026: 2,042,494 sharesMay 15, 2026: 2,057,094 sharesMay 29, 2026: 2,071,713 sharesJun 15, 2026: 2,087,557 sharesJun 30, 2026: 2,078,902 sharesJul 15, 2026: 2,118,780 sharesJul 31, 2026: 2,142,523 sharesAug 14, 2026: 2,158,099 sharesAug 31, 2026: 2,306,196 sharesSep 15, 2026: 120,606 sharesSep 30, 2026: 123,890 sharesOct 15, 2026: 114,402 sharesOct 30, 2026: 134,896 shares
Short interest in CTSO by settlement date
Settlement dateShort interestChangeChange %Avg. daily volumeDays to cover
Oct 30, 2026134.9K+20.5K+17.9%121.5K1.11
Oct 15, 2026114.4K−9.49K−7.7%11.1K10.27
Sep 30, 2026123.9K+3.28K+2.7%10.3K11.98
Sep 15, 2026Split120.6K−2.19M−94.8%45.6K2.65
Aug 31, 20262.31M+148.1K+6.9%126.0K18.30
Aug 14, 20262.16M+15.6K+0.7%72.2K29.87
Jul 31, 20262.14M+23.7K+1.1%55.9K38.34
Jul 15, 20262.12M+39.9K+1.9%78.9K26.86
Jun 30, 20262.08M−8.65K−0.4%333.4K6.23
Jun 15, 20262.09M+15.8K+0.8%264.3K7.90
May 29, 20262.07M+14.6K+0.7%111.9K18.52
May 15, 20262.06M+14.6K+0.7%99.8K20.60
Apr 30, 20262.04M−1.82K−0.1%43.3K47.19
Apr 15, 20262.04M+23.6K+1.2%84.0K24.34
Mar 31, 20262.02M+2.02K+0.1%134.5K15.02
Mar 13, 20262.02M+17.8K+0.9%73.1K27.61
Feb 27, 20262.00M−38.4K−1.9%51.1K39.14
Feb 13, 20262.04M+2.77K+0.1%77.5K26.32
Jan 30, 20262.04M+50.6K+2.6%78.9K25.80
Jan 15, 20261.99M−16.7K−0.8%68.8K28.85
Dec 31, 20252.00M+6.68K+0.3%151.3K13.24
Dec 15, 20252.00M−17.3K−0.9%121.5K16.43
Nov 28, 20252.01M+61.3K+3.1%124.0K16.23
Nov 14, 20251.95M+385.9K+24.6%142.9K13.66
Oct 31, 20251.57M+248.9K+18.9%79.2K19.78
Oct 15, 20251.32M−24.8K−1.9%71.3K18.48
Sep 30, 20251.34M−6.55K−0.5%86.4K15.53
Sep 15, 20251.35M−38.6K−2.8%58.5K23.05
Aug 29, 20251.39M−102.6K−6.9%186.1K7.45
Aug 15, 20251.49M+122.4K+9.0%523.5K2.85
Jul 31, 20251.37M−71.6K−5.0%68.3K20.01
Jul 15, 20251.44M−42.9K−2.9%129.8K11.09
Jun 30, 20251.48M+48.4K+3.4%141.4K10.48
Jun 13, 20251.43M−30.3K−2.1%74.5K19.25
May 30, 20251.46M−21.3K−1.4%93.7K15.62
May 15, 20251.49M−20.0K−1.3%195.7K7.59
Apr 30, 20251.51M−119.9K−7.4%68.5K21.97
Apr 15, 20251.62M−120.6K−6.9%76.4K21.27
Mar 31, 20251.75M−96.4K−5.2%70.8K24.66
Mar 14, 20251.84M−8.02K−0.4%103.3K17.83
Feb 28, 20251.85M−100.5K−5.2%126.2K14.65
Feb 14, 20251.95M+16.2K+0.8%178.2K10.95
Jan 31, 20251.93M+101.2K+5.5%80.3K24.10
Jan 15, 20251.83M+385.5K+26.6%996.8K1.84
Dec 31, 20241.45M+50.2K+3.6%177.6K8.15
Dec 13, 20241.40M+27.9K+2.0%154.4K9.05
Nov 29, 20241.37M+70.5K+5.4%103.6K13.22
Nov 15, 20241.30M−56.8K−4.2%195.4K6.65
Oct 31, 20241.36M+7.06K+0.5%97.1K13.97

Fails-to-deliver

Shares that weren't delivered by the settlement date, from the SEC, for the last 30 dates with fails. The price is the previous day's closing price published by the SEC.

Fails-to-deliver in CTSO by settlement date
Settlement dateSharesPriceValue
Oct 9, 2026755$3.73$2.82K
Oct 8, 202636$3.87$139.32
Oct 7, 20261,468$3.96$5.81K
Oct 2, 2026390$4.05$1.58K
Sep 25, 20267$4.35$30.45
Sep 24, 2026185$5.02$928.7
Sep 17, 202696$5.73$550.08
Sep 16, 202665$6.06$393.9
Sep 15, 2026751$5.75$4.32K
Sep 14, 20264,859$6.41$31.1K
Sep 10, 2026856$6.33$5.42K
Sep 9, 2026481$6.76$3.25K
Sep 2, 202611$0.34$3.74
Sep 1, 20261,646$0.34$559.64
Aug 26, 20262,737$0.36$985.32
Aug 14, 20263,929$0.36$1.41K
Jul 29, 20261$0.37$0.37
Jul 28, 202678$0.36$28.08
Jul 23, 20267,838$0.38$2.98K
Jul 2, 202620,709$0.39$8.08K
Jun 23, 202682$0.41$33.62
Jun 22, 2026960$0.44$422.4
Jun 15, 202657,180$0.40$22.9K
Jun 12, 202630$0.39$11.7
Jun 4, 202633,042$0.49$16.2K
Jun 1, 20261,741$0.49$853.09
May 29, 20263,909$0.50$1.95K
May 28, 2026913$0.49$447.37
May 26, 20263,707$0.46$1.71K
May 22, 20264,314$0.46$1.98K

Daily short volume

Off-exchange short-sale volume, not short interest: shares sold short each day in trades reported to FINRA, for the last 30 trading days.

The short volume ratio isn't a sentiment gauge: market makers sell short to fill buy orders and to hedge, so short sales are usually about half of off-exchange volume.

Off-exchange short volume in CTSO by trade date
Trade dateShort volumeShort exemptOff-exchange volumeShort volume ratio
Nov 10, 202623706,3493.7%
Nov 9, 20265,057018,68927.1%
Nov 6, 20264,07506,37463.9%
Nov 5, 20265,7388115,96635.9%
Nov 4, 20263,4391195,90258.3%
Nov 3, 20264,2731665,32380.3%
Nov 2, 20261,1822010,12011.7%
Oct 30, 20264,2631,45614,17830.1%
Oct 29, 20261,6805922,4867.5%
Oct 28, 20261,57306,18525.4%
Oct 27, 20264,0971,69613,13531.2%
Oct 26, 202614,1022,60822,38963.0%
Oct 23, 20262,3783222,28210.7%
Oct 22, 202613,572042,01432.3%
Oct 21, 202611,157023,71847.0%
Oct 20, 20268,062028,88927.9%
Oct 19, 202670,138798134,84052.0%
Oct 16, 2026267,2741,332380,75970.2%
Oct 15, 20261,9439488,04024.2%
Oct 14, 20265,49467311,47347.9%
Oct 13, 202691804,56620.1%
Oct 12, 20262,41606,63736.4%
Oct 9, 20261,11703,32333.6%
Oct 8, 20263,09205,47456.5%
Oct 7, 202681002,82828.6%
Oct 6, 2026880013,7136.4%
Oct 5, 20261,57902,97453.1%
Oct 2, 20263,44904,50476.6%
Oct 1, 20261,59013,44446.2%
Sep 30, 20265,55506,80681.6%

ATS (dark pool) volume

Weekly volume on alternative trading systems (ATS) and other off-exchange (OTC) venues, from FINRA, for the last 12 weeks. ATS share is ATS volume ÷ (ATS + OTC volume), not a share of all trading.

Weekly ATS and OTC volume in CTSO
Week ofTierATS sharesATS tradesOther OTC sharesOther OTC tradesATS share
Oct 5, 2026T26,18828822,2791,10421.7%
Sep 28, 2026T25,09837224,5501,66817.2%
Sep 21, 2026T24,9097433,3851,08412.8%
Sep 14, 2026T23,7759917,3441,53017.9%
Sep 7, 2026T29,37316338,20413,49919.7%
Aug 31, 2026T2247,2416,4334,637,66850,1815.1%
Aug 24, 2026T239,363408303,76882811.5%
Aug 17, 2026T260,038336526,04177110.2%
Aug 10, 2026T213,690757215,3707286.0%
Aug 3, 2026T212,045356247,1095784.6%
Jul 27, 2026T28,56440241,2266733.4%
Jul 20, 2026T24,206305125,1774733.3%